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1
Lucca, Rosemeire Aparecida da Silva de. "Propriedades físico-químicas da lectina KM+ monitoradas por dicroismo circular (CD) e fluorescência. Estimativa do conteúdo de estrutura secundaria por CD". Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-02042014-100315/.
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Uma nova lectina extraída da semente de Artocarpus integrifólia, denominada KM+ foi recentemente descrita. KM+ e haptotática para neutrófilos, promove a aglutinação de hemácias dos grupos A, B, 0, estimula a proliferação de linfócitos do baço de camundongos e liga-se em α D-manose, α metil manosidio e α D-glicose. Esta lectina é composta por quatro monômeros, com peso molecular de 13.150 daltons cada, unidos por interações não covalentes. KM+ contem 1,8% de carboidratos e apresentou quatro isoformas com pontos isoelétricos entre 4,2 e 5,2. Este trabalho teve como objetivos estudar modificações estruturais de KM+ em função de parâmetros como temperatura, força iônica, pH, agentes desnaturantes, ligação com D-manose, monitoradas por dicroísmo circular (CD) e fluorescência. CD também foi utilizado para estimar o conteúdo de estrutura secundaria de KM+, utilizando-se dois programas descritos na literatura: SSE (Secondary Structure Estimation), que utiliza o método dos mínimos quadrados para a estimativa da estrutura secundaria e obtenção dos espectros básicos, baseados nos dados cristalográficos de proteínas de .estrutura resolvida; CCA (Convex Constraint Analisys) que utiliza o algoritmo simplex e a partir dos espectros de CD das proteínas de referencia calcula os espectros das componentes básicas. Para a estimativa das frações de estrutura secundária o segundo método utiliza o programa Lincomb. Os espectros de CD foram registrados no intervalo de 185 a 260 nm. O conteúdo em estrutura secundária, estimado pelo programa SSE foi: 0% de α-hélice, 41% de folha β, 27% de volta β e 32,3 de estrutura desordenada; pelo programa CCA foi: 1% de α-hélice, 35% de folha β anti-paralela, 21% de volta β e/ou folha β paralela, 15% de contribuições de aromáticos e/ou ligações dissulfeto, 28% de estrutura desordenada. Os desvios médios quadráticos para os programas SSE e CCA foram 12% e 1%, respectivamente. Portanto a lectina KM+ é principalmente constituída por estruturas tipo folha β e tipo desordenada. A curva calculada pelo programa CCA foi mais bem estimada, pois tem o desvio médio quadrático 12 vezes menor que o do programa SSE. Este resultado, provavelmente ocorre devido aos seguintes fatores: (i) no programa CCA, o espectro da proteína a ser analisada e alinhado com os espectros das proteínas de referência, influenciando no calculo dos espectros básicos; (ii) maior número de proteínas com estrutura β no grupo de referência do programa CCA. A estabilidade de KM+ em função da temperatura tem comportamento diferente em tampão sódio fosfato (PBS) daquele observado em água. Em PBS, quando a amostra esta a 70°C, a forma do espectro de CD mostrou-se consistente com um espectro de proteína desnaturada. Comumente, um espectro de proteína desnaturada caracteriza-se pela perda da estrutura secundaria predominante e aumento da estrutura desordenada. Em água, também a 70°C, na região da estrutura β (216 nm) surge uma nova banda e na região da estrutura desordenada (195 nm) aparece uma banda com valores positivos mimetizando um espectro da estrutura α-hélice. Esta diferença de comportamento pode ser devida à força iônica. A desorganização promovida na molécula de KM+ por cloreto de guanidina foi típica de desnaturação. o máximo da emissão de fluorescência, da KM+ em PBS pH 7,2, foi a 328 nm, característico de resíduos de triptofano protegidos do solvente. Este máximo mudou para 340 nm em pH 10,5. Este resultado indica mudanças no ambiente químico do triptofano neste pH. O deslocamento para a região do vermelho indica, que em pH. os resíduos de triptofano estio em maior contato com o solvente. O número de sitios ligantes de D-manose J)a molécula de KM+, foi estimado pela supressão da fluorescência promovida pelo D-manose. Esta estimativa foi baseada na suposição de que todos os sítios ligantes de D-manose estivessem próximos aos resíduos de triptofano. A relação encontrada foi de 2 moles de D-manose/mol de KM+Recently a new lectin, KM+, isolated from Artocarpus integrifolia seeds was described. KM+ induces neutrophil migration, agglutination of human red blood cells, proliferation of mouse spleen cells and binding with monosacharides D-mannose, D-glicose and α-metil mannoside. This glycoprotein is composed of four monomers, assembled by non covalent bonds, has 500 aminoacids residues/mol, with a Molecular Weight of 52,000 Daltons and 1.8% of carbohydrates [27]. In this work structural changes of KM+ was studied as a function of temperature, pH, chemical denaturing agents as well as the binding with D-mannose. These changes were monitored by circular dichroism (CD) and fluorimetry. Circular Dichroism (CD) spectroscopy was used for the analysis of the secondary structure of KM+ in solution due do its capacity to indicate the presence and to estimate the proportion of α-helix, β-sheet, β-turn and unordered conformations. This measurent can be regarded as a function of the relative orientation of the chromophores responsible for their chiroptical activity. CD spectroscopy is also one of the methods of choice for monitorization of conformational changes in proteins as a function of solvents, pH, temperature, ionic strength and specific or non specific binding. Two programs which are in use for estimation of secondary structure: SSE, using the linear least squares method and CCA, using the simplex method, were evaluated in the present work. SSE uses a set of proteins with known X-ray data as the basis for evaluation while CCA uses only pure proteins experimental CD spectra. Fluorescence spectroscopy is very useful to monitore of protein conformational changes in solution due to the presence of intrinsic fluorophores. Fluorescence Measurements were performed at 25°C. Samples were excited at 280 nm and the emission was monitored in the range 290-450 nm. The maximum emission as a function of pH was at pH 7.0. The wavelength for maximum emission changed from 328 nm at pH 7.0 to 340 nm at pH 10.5. CD spectra were recorded over the range of 185 up to 260 nm. The Secondary structure content estimated by SSE program was: 0% α-helix, 41% β-sheet, 26% β-turn and 32% random with RMS of 12% and CCA program was: 1% α-helix, 35% antiparallel β-sheet, 21% β-turn and/or parallel B-sheet, 28% random, 15% aromatics contributions and dissulfide linkages with RMS of 1%. The fractions of secondary structure obtained when using CCA program were more consistent than those of SSE program. The simulation by CCA program was better probably due to its desconvolution of the spectral contribution of the common secondary structures using experimental CD curves of proteins. The stability of KM+, in PBS, as a function of temperature changes above 55°C but only at 70°C the shape of the CD spectrum is consistent with the loss of the native ordered secondary structure that should accompany protein unfolding. CD spectra of KM+ in water showed conformational changes as a function of temperature was not consistent with denaturated proteins. The unfolding of KM+ by GdnCl and SDS resulted in CD spectroscopic changes: consistent with the increased random structure and disappearance of beta sheet. Using the two denaturing agents together GdnCl and temperature, the denaturation was observed at lower decreased both GdnCl concentration and at lower temperature. The estimation of the number of binding sites for D-mannose was obtained through the fluorescence intensity decrease due to a quenching effect of D-mannose and showed that the stoichiometry of binding was 2 moles of D-mannoseimol of lectin
2
Silva, Luana Maria Castelo Melo. "Efeito da lectina da alga marinha vermelha Pterocladiella capillace em feridas limpas induzidas em ratos". reponame:Repositório Institucional da UFC, 2012. http://www.repositorio.ufc.br/handle/riufc/18834.
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SILVA, Luana Maria Castelo Melo. Efeito da lectina da alga marinha vermelha Pterocladiella capillace em feridas limpas induzidas em ratos. 2012. 135 f. Tese (Doutorado em bioquímica)- Universidade Federal do Ceará, Fortaleza-CE, 2012.Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-07-20T16:16:36Z No. of bitstreams: 1 2012_tese_lmcmsilva.pdf: 10225620 bytes, checksum: 67dadb7130fbee0f6137beb9f3cec43e (MD5)
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Based on the need for new formulations that are more efficient and on the properties provided by molecules derived from seaweed, it is believed that these can be effective in healing process. The lectin from the red seaweed Pterocladiella capillacea (PcL) and the polysaccharides of red algae Solieria filiformis (SfP) were initially analyzed in toxicity testing. PcL was applied to the paw edema test followed by measurement of myeloperoxidase (MPO). We evaluated the effect of the seaweed Pterocladiella capillacea lectin (PcL) and algal polysaccharides Solieria filiformis (SfP) in healing wounds in rats induced. Both molecules were submitted to microbiological tests and assayed for the effect on wound healing in wounds clean induced on the back of rats. SfP was used as a possible vehicle for the administration of PcL and compared to Carbopol 940 (C). The gels (0.9%) were analyzed rheological and then applied to the lesions during a treatment period of 10 days, using kollagenase ® as control. The healing process was evaluated on the size of the wounds, levels of MPO and histological analysis. The molecule SfP and PcL is not toxic for the parameters of body weight, organ and biochemical measurements. However, the histological analysis showed minor changes in liver and kidney. PcL (1, 3 and 9 mg / kg, i.v) reduced the edema induced by carrageenan and its inhibitor when administered with mucin was not possible to check the reduction of edema which was confirmed by measurement of MPO. The two molecules were used in microbiological assays and not inhibit growth of any microorganism tested and unable to use SfP as carbon source. The rheological analysis showed that the SfP used in the formulation of the gels (PcL+SfP and SfP) had the characteristic of a pseudoplastic. Macroscopic analysis of wounds showed a reduction in lesion area in the animals treated with PCL, PCL+SfP, PCL+C (53.5 and 60% respectively) on the sixth day of administration. In histological analysis, there was no severe inflammatory infiltrate in the tissues obtained until 4th day of administration of the gels (PcL and PcL+SfP, PcL+C) and Kollagenase® (positive control). On day 6, the untreated animals and those treated only with SfP showed inflammatory infiltrate. The measurement of MPO showed a reduction in the inflammatory process in the samples containing PcL, whose results corroborate the histological analysis. In conclusion, PcL aid in wound repair, suggesting its use as a possible future tool for the treatment of lesions. The biological and pharmacological role of lectins and polysaccharides of seaweed is part of a study area little explored, where a lot of knowledge should be invested since these biomolecules can be promising for the pharmaceutical industry.
Com base na necessidade de obter novas formulações mais eficientes e diante das propriedades apresentadas pelas moléculas oriundas de algas marinhas, acredita-se que estas possam ser eficazes no processo de cicatrização. A lectina da alga marinha vermelha Pterocladiella capillacea (PcL) e os polissacarídeos da alga vermelha Solieria filiformis (SfP) inicialmente foram analisados em ensaio de toxicidade. PcL foi aplicada no ensaio do edema de pata seguido da dosagem de mieloperoxidase (MPO). Avaliou-se o efeito da lectina da alga Pterocladiella capillacea (PcL) e os polissacarídeos das algas Solieria filiformis (SfP) na cicatrização de feridas induzidas em ratos. Ambas as moléculas foram submetidas a ensaios microbiológicos e analisadas quanto ao efeito no processo de cicatrização em feridas limpas induzidas no dorso de ratos. SfP foi utilizado como um possível veículo para a administração de PcL e comparado ao Carbopol 940 (C). Os géis (0,9%) foram submetidos a análise reológica e então aplicados nas lesões durante um período de tratamento de 10 (dez) dias, utilizando kollagenase® como controle. O processo de cicatrização foi avaliado quanto ao tamanho das feridas, dosagem de MPO e análise histológica. PcL e SfP não demonstraram toxicidade quanto aos parâmetros de peso corpóreo, órgãos e dosagens bioquímicas. Entretanto a análise histológica mostrou pequenas alterações no fígado e rim. PcL (1, 3 e 9 mg/kg, i.v.) reduziu o edema induzido por carragenana e quando administrada com seu inibidor mucina não foi possível verificar a redução do edema o qual foi confirmado pela dosagem de MPO. As duas moléculas foram aplicadas em ensaios microbiológicos e não inibiram o crescimento de nenhum micro-organismo testado, os quais também não foram capazes de utilizar SfP como fonte de carbono. A análise reológica mostrou que os SfP utilizados na formulação dos géis (PcL+SfP e SfP) apresentaram a característica de um pseudoplástico. A análise macroscópica das feridas mostrou uma redução da área da lesão nos animais tratados com PcL+SfP e PcL+C (53,5 e 60%, respectivamente) no sexto dia de administração. Na análise histológica, não foi observado infiltrado inflamatório acentuado nos tecidos obtidos até o 4º dia da administração dos géis (PcL+SfP e PcL+C) e Kollagenase® (controle positivo). No 6º dia, os animais não tratados e os tratados apenas com SfP mostraram infiltrado inflamatório. A dosagem de MPO demonstrou redução no processo inflamatório nas amostras contendo PcL, cujo resultado corrobora com a análise histológica. Em conclusão, PcL auxiliou no reparo de feridas, sugerindo seu uso futuro como uma possível ferramenta para o tratamento de lesões. O papel biológico e farmacológico das lectinas e polissacarídeos de algas marinhas faz parte de uma área de estudos ainda pouco explorada, onde muito conhecimento deverá ser investido visto que estas biomoléculas podem ser promissoras para a indústria farmacêutica.
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Oliveira, Wilian Rosário de. "Lectinas de Crotalaria spectabilis R.: isolamento, purificação e atividade aglutinante em Leptospira biflexa (saprófita) e L. interrogans (patogênica)". Instituto de Ciências da Saúde, 2014. http://repositorio.ufba.br/ri/handle/ri/23507.
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CAPES
Lectinas são proteínas que se ligam especificamente a resíduos de açúcar e estão envolvidas no processo de reconhecimento celular e sinalização em diversas vias metabólicas. O objetivo deste estudo foi isolar, purificar e investigar a atividade biológica das lectinas de Crotalaria spectabilis R. quanto a sua capacidade de hemaglutinação e aglutinação das linhagens bacterianas: Leptospira biflexa e L. interrogans. Para extração das proteínas, as sementes foram moídas e suas células lisadas em solução NaCl 0,15 M. Após essa etapa, as proteínas foram precipitadas com acetona e sulfato de amônio, dialisadas, liofilizadas e purificadas por cromatografia de filtração e troca iônica. A quantificação proteica foi realizada pelo método de Bradford e o perfil eletroforético obtido por SDS-PAGE. Para testar a atividade biológica das lectinas foram utilizados ensaios de hemaglutinação bem como de aglutinação das linhagens bacterianas. Em nossos resultados, o método de precipitação proteica por acetona resultou em maior extração quando comparado ao método por sulfato de amônio. A lectina de C. spectabilis R. apresentou um peso molecular de 30 kDa e os ensaios de hemaglutinação foram positivos para a proteína. Assim, concluimos que nas sementes de C. spectabilis R. existem lectinas com capacidade de reconhecer receptores presentes na membrana de eritrócitos humanos e promover aglutinação celular. Por fim, as lectinas da planta C. spectabilis R. também foram capazes de aglutinar L. interrogans e L. biflexa, sendo esta reposta mais acentuada na linhagem patogênica.
Lectins are proteins that bind carbohydrate residues with affinity and are involved in the process of cell recognition and signaling in different metabolic pathways. The aim of this study was to isolate, purify and investigate the biological activity of the Crotalaria spectabilis R. lectins in terms of hemagglutination and agglutination capacity of the bacterial strains: Leptospira biflexa and L. interrogans. For protein extraction, the seeds were milled and their cells lysed in 0,15 M NaCl solution. After this step, the proteins were precipitated with acetone and ammonium sulfate, dialyzed, lyophilized and purified by filtration chromatography and ion exchange, respectively. Protein quantification was performed by the Bradford method and the electrophoretic profile by SDS-PAGE. For testing the biological activities of lectins, hemagglutination assays were used as well agglutination of the bacterial strains. In our results, protein precipitation method by acetone resulted in higher yield when compared to ammonium sulfate. The C. spectabilis R. lectin presented a molecular weight of 30 kDa and the hemagglutination assays were positives for the protein. Thus, we conclude that in the C. spectabilis R. seeds there are lectins with capacity to recognize receptors present in the human erythrocytes membrane and to promote cell agglutination. At last, the seed lectin C. spectabilis R. was also able to agglutinate L. interrogans and L. biflexa, this response being stronger in the pathogenic strain.
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Bibi, Rashda. "Synthèse de nouveaux dérivés osidiques pour le ciblage de lectines originales". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2012. http://www.theses.fr/2012ENCM0002.
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Les lectines spécifiques du rhamnose ont été découvertes comme nouvelle classe de lectines dans les années 1990. La plupart de ces lectines a été isolée à partir d'animaux aquatiques. Des récepteurs spécifiques du rhamnose sur les kératinocytes ont été découverts en 1991 quand les reconnaissances entre des glycoprotéines synthétiques incorporées dans des liposomes et des kératinocytes ont été étudiées. Nous avons synthétisé des nouveaux dérivés de rhamnose à cibler ces lectinesRhamnose binding lectines were discovered as new class of lectines in 1990's. Most of these lectines has been isolated from aquatic animals. It was discovered in 1991 that rhamnose specific receptors may be present in human skin while studying the interaction between liposomes incorating synthesitic glycoproteins and keratinocytes. We have synthesized new derivatives of rhamnose to target these lectines
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Santos, Adriano dos [UNESP]. "Estudo da afinidade das proteínas rTgMIC1 e rTgMIC4 da Toxoplasma gondii com fetuína e asialofetuína utilizando técnica piezelétrica". Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/92055.
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santos_a_me_araiq.pdf: 1458862 bytes, checksum: f7fe58d688854cba187d0f1e30f22ce7 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
As proteínas de micronema TgMIC1 e TgMIC4 (TgMICs) da Toxoplasma gondii fazem parte de um complexo proteico localizado na superfície do parasita responsável pelo processo de adesão e invasão celular. Os objetivos desse trabalho foram estudar dispositivos piezelétricos contendo em cada um, uma das MICs recombinantes (rTgMIC1 ou rTgMIC4) e utilizá‐los na determinação das constantes de afinidade entre elas com a fetuína e asialofetuína, empregando o modelo da Isoterma de Langmuir. Os dispositivos foram desenvolvidos por meio a abordagem de monocamadas automontadas (SAM) mista de tióis, utilizando solução etanólica contendo 2,5 mM de ácido 11‐mercaptoundecanóico (11‐MUA) e 7,5 mM de 6‐mercapto‐1‐hexanol (C6OH). A formação da SAM, realizada em temperatura ambiente por 12 h, foi monitorada pela técnica de Microbalança a Cristal de Quartzo com Fator Dissipativo (QCM‐D) e voltametria cíclica utilizando o par redox [FeII(CN)6]4‐/ FeIII(CN)6]3‐. Os resultados obtidos por ambas as técnicas evidenciaram a formação de SAM rígida e de elevado grau de cobertura superficial após cinética lenta em que processos de adsorção e organização dos tióis ocorreram simultaneamente. Para a imobilização das rTgMICs, solução aquosa contendo 10 mM de EDC (N‐etil‐N‐(dimetilaminopropil) carbodiimida) e 20 mM de NHS (N‐hidroxisuccinimida) foi utilizada para a ativação dos grupos carboxílicos presentes na SAM por 2 h, e o processo acompanhado por QCM‐D apresentou resultados compatíveis com aqueles encontrados na literatura. Pela mesma técnica, foi possível verificar que ambas as rTgMICs se imobilizam sobre o cristal de quartzo após sua incubação com solução 0,15 mg/mL de cada rTgMIC em tampão Tris‐HCl contendo 200 mM de NaCl...
The Toxoplasma gondii micronemal proteins TgMIC1 and TgMIC4 (TgMICs) are part of a protein complex located on the surface of the parasite responsible for the process of cellular adhesion and invasion. The goal of the present work was to study a piezoelectric device containing the recombinant MICs (rTgMIC1 or rTgMIC4) and use it in determining the affinity constants between the MICs with fetuin and asialofetuin, employing the Langmuir isotherm model. The devices were developed using the approach of self‐assembled monolayer (SAM) in ethanolic solution containing 2.5 mM of 11‐mercaptoundecanoic acid (11‐MUA) and 7.5 mM of 6‐mercaptohexanol (C6OH). The SAM formation, held at room temperature for 12 h, was monitored by the Quartz Crystal Microbalance technique with Dissipative Factor (QCM‐D) and cyclic voltammetry using the redox couple [FeII(CN)6]4‐/FeIII(CN) 6]3‐. The results obtained from both techniques showed the formation of a rigid and high surface degree coverage SAM after a slow kinetic process in which adsorption and organization of the thiols occur simultaneously. For the immobilization of rTgMICs, aqueous solution containing 10 mM EDC N‐ethyl‐N‐(dimethylaminopropyl) carbodiimide and 20 mM NHS (N‐hydroxysuccinimide) was used for 2 h, and the process followed by QCM‐D was consistent with those found in the literature. By the same technique it was found that both rTgMICs are immobilized on the quartz crystal after incubation whit solution 0.15 mg/mL of each rTgMIC in Tris‐HCl containing 200 mM NaCl (pH 8.0) for 2 h. Unlike the functionalization of the quartz crystal rTgMIC4, remaining adsorption sites were observed in the process using the rTgMIC1, wherein the blocking step using 0.1% gelatin solution for 2 h was required. Throughout the QCM‐D technique it was possible... (Complete abstract click electronic access below)
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Santos, Adriano dos. "Estudo da afinidade das proteínas "rTgMIC1" e "rTgMIC4" da Toxoplasma gondii com fetuína e asialofetuína utilizando técnica piezelétrica /". Araraquara : [s.n.], 2012. http://hdl.handle.net/11449/92055.
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Orientador: Paulo Roberto BuenoBanca: Emanuel Carrilho
Banca: Maria Cristina Roque Antunes Barreira
Resumo: As proteínas de micronema TgMIC1 e TgMIC4 (TgMICs) da Toxoplasma gondii fazem parte de um complexo proteico localizado na superfície do parasita responsável pelo processo de adesão e invasão celular. Os objetivos desse trabalho foram estudar dispositivos piezelétricos contendo em cada um, uma das MICs recombinantes (rTgMIC1 ou rTgMIC4) e utilizá‐los na determinação das constantes de afinidade entre elas com a fetuína e asialofetuína, empregando o modelo da Isoterma de Langmuir. Os dispositivos foram desenvolvidos por meio a abordagem de monocamadas automontadas (SAM) mista de tióis, utilizando solução etanólica contendo 2,5 mM de ácido 11‐mercaptoundecanóico (11‐MUA) e 7,5 mM de 6‐mercapto‐1‐hexanol (C6OH). A formação da SAM, realizada em temperatura ambiente por 12 h, foi monitorada pela técnica de Microbalança a Cristal de Quartzo com Fator Dissipativo (QCM‐D) e voltametria cíclica utilizando o par redox [FeII(CN)6]4‐/ FeIII(CN)6]3‐. Os resultados obtidos por ambas as técnicas evidenciaram a formação de SAM rígida e de elevado grau de cobertura superficial após cinética lenta em que processos de adsorção e organização dos tióis ocorreram simultaneamente. Para a imobilização das rTgMICs, solução aquosa contendo 10 mM de EDC (N‐etil‐N‐(dimetilaminopropil) carbodiimida) e 20 mM de NHS (N‐hidroxisuccinimida) foi utilizada para a ativação dos grupos carboxílicos presentes na SAM por 2 h, e o processo acompanhado por QCM‐D apresentou resultados compatíveis com aqueles encontrados na literatura. Pela mesma técnica, foi possível verificar que ambas as rTgMICs se imobilizam sobre o cristal de quartzo após sua incubação com solução 0,15 mg/mL de cada rTgMIC em tampão Tris‐HCl contendo 200 mM de NaCl... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Toxoplasma gondii micronemal proteins TgMIC1 and TgMIC4 (TgMICs) are part of a protein complex located on the surface of the parasite responsible for the process of cellular adhesion and invasion. The goal of the present work was to study a piezoelectric device containing the recombinant MICs (rTgMIC1 or rTgMIC4) and use it in determining the affinity constants between the MICs with fetuin and asialofetuin, employing the Langmuir isotherm model. The devices were developed using the approach of self‐assembled monolayer (SAM) in ethanolic solution containing 2.5 mM of 11‐mercaptoundecanoic acid (11‐MUA) and 7.5 mM of 6‐mercaptohexanol (C6OH). The SAM formation, held at room temperature for 12 h, was monitored by the Quartz Crystal Microbalance technique with Dissipative Factor (QCM‐D) and cyclic voltammetry using the redox couple [FeII(CN)6]4‐/FeIII(CN) 6]3‐. The results obtained from both techniques showed the formation of a rigid and high surface degree coverage SAM after a slow kinetic process in which adsorption and organization of the thiols occur simultaneously. For the immobilization of rTgMICs, aqueous solution containing 10 mM EDC N‐ethyl‐N‐(dimethylaminopropyl) carbodiimide and 20 mM NHS (N‐hydroxysuccinimide) was used for 2 h, and the process followed by QCM‐D was consistent with those found in the literature. By the same technique it was found that both rTgMICs are immobilized on the quartz crystal after incubation whit solution 0.15 mg/mL of each rTgMIC in Tris‐HCl containing 200 mM NaCl (pH 8.0) for 2 h. Unlike the functionalization of the quartz crystal rTgMIC4, remaining adsorption sites were observed in the process using the rTgMIC1, wherein the blocking step using 0.1% gelatin solution for 2 h was required. Throughout the QCM‐D technique it was possible... (Complete abstract click electronic access below)
Mestre
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Destecroix, Harry. "Anthracene based synthetic lectins". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682557.
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Over the past 40 years there has been substantial interest in continuous glucose monitors (CGMs) for diabetes management. Much of the work has focused on the use of enzymes, lectins (carbohydrate binding proteins) or boronic acids as the sensing element, but instability and biocompatibility has hindered development. This has presented an 0pp0l1unity for supramolecular chemists to make synthetic lectins for glucose that respond in real time to glucose in the blood. However, carbohydrate recognition in water presents a challenge due to the hydromimetic nature of the substrate. Moreover, subtle structural differences between monosaccharides makes selectivity problematic. Despite these difficulties, our group has met with some success in designing synthetic lectins over the past decade. Recently we reported a simple monocyclic receptor An-L 34 for glucose which is accessible in only 5 steps with 23% overall yield. The receptor binds glucose with excellent selectivity over physiological blood glucose levels, displaying increases in fluorescence emission suggesting its potential as a CGM. We report the development of a series of receptors based on the new architecture. New synthetic procedures have provided access to asymmetrical systems that have highlighted the driving forces behind binding. 2nd and 3rd generation dendritic solubilising groups have been synthesised leading to receptors that are less prone to aggregation and with enhanced affinity for glucose and improved optical properties for sensing. The improvements are attributed to the interaction of the carboxylate groups with the sugar from the larger solubilising groups. Using this approach a new receptor with 100 fold selectivity for positively charged monosaccharide glucosamine has been demonstrated. The new generation systems have been screened in human blood plasma, with the 2nd generation systems showing enhancements in response to glucose. Furthermore work has started towards immobilisation of receptors for fibre optic sensing.
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Andersson, Pontus. "Comparison of Lectins and their suitability in Lectin Affinity Chromatography for isolation of Glycoproteins". Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-417024.
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Virtually all extracellular proteins in humans are glycoproteins and likewise are many biopharmaceuticals. The glycosylation is directly correlated to biological function and stability of these proteins. The ability to isolate glycoproteins is thus of great importance in many applications. The most common isolation method for glycoproteins is affinity chromatography using lectins, a ubiquitous and versatile group of carbohydrate-binding proteins. The lectin Concanavalin A (ConA) has long been used for this purpose but suffers from undesired leakage into the eluate, causing an inquiry of alternative chromatography ligands or optimization of the ConA resin.In this study, a total of 20 different lectins, including ConA, were evaluated and compared in terms of suitability as ligands in affinity chromatography for glycoprotein isolation. The lectins’ binding to glycoproteins were studied, mainly through microtiter plate binding assays using a monoclonal IgG1 antibody and Conalbumin (Ovotransferrin). Further, sugar-specificities and potential eluting sugars for the lectins were examined through inhibition with eight different carbohydrates. Additionally, the glycoprotein binding and leakage of ConA columns were examined, and a potential leakagereducing treatment of ConA resin evaluated.ConA was found to be superior in binding to the investigated glycoproteins but exhibited a limited binding when immobilized to an agarose resin. This discrepancy is likely a consequence of structurally hidden glycans on the used glycoproteins and requirements of long residence time when used in a chromatographic setting. Binding competition with several sugars were investigated with a similar microtiter plate binding assay. This method displayed potential to predict the behaviour of sugars and their suitability as eluting agents in a chromatography column. The best eluting sugar for ConA was showed to be methylmannoside, ideally in combination with methylglucoside. Lastly, evaluation of ConA columns with a crosslinking glutaraldehyde-treatment showed that the ConA ligand leakage may be significantly reduced, although further studies and optimizations are needed.This study thus presents a repertoire of lectins and their differences in terms of glycoprotein-binding and sugar-specificity, as well as evaluations of ConA columns’ efficiency and potential leakage-prevention.
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Sousa, Bruno Lopes de. "CaracterizaÃÃo estrutural das formas silvestre e recombinante de uma lectina de sementes de Vatairea macrocarpa Benth e anÃlise das suas bases moleculares de ligaÃÃo ao antÃgeno Tn". Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13196.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoAs lectinas consitem em uma classe diversificada de proteÃnas, capazes de reconhecer estruturas glicÃdicas de forma reversÃvel e com alta especificidade, no entanto sem alterar suas estruturas quÃmicas, participando de vÃrios processos celulares importantes. Dentre as diferentes famÃlias de lectinas, as isoladas a partir de leguminosas sÃo as mais extensivamente estudadas, havendo sido relatada a influÃncias dessas molÃculas sobre diversos processos patolÃgicos, incluindo a carcinogÃnese. NotÃveis propriedades antitumorais tÃm sido detectadas para algumas lectinas de leguminosas, resultantes da sua habilidade em induzir a morte celular ou a autofagia em cÃlulas cancerÃgenas, o que atraÃdo atenÃÃo para suas possiveis aplicaÃÃes biomÃdicas. AlÃm disso, algumas lectinas desse grupo especificas para galactose/N-acetil-D-galactosamina (Gal/GalNAc) tÃm se mostrado Ãteis como marcadores histoquÃmicos na pesquisa do cÃncer e a caracterizaÃÃo estrutural dessas lectinas em complexo com diferentes epÃtopos cancerÃgenos vem sendo realizada com sucesso. A lectina isolada a partir das sementes da leguminosa Vatairea macrocarpa (VML) à uma lectina bem caracterizada especÃfica para Gal/GalNAc capaz de reconhecer especificamente o antÃgeno Tn (GalNAc-α-O-Ser), naturalmente encontrado em O-mucinas presentes em diferentes tipos de cÃncer. As estruturas cristalogrÃficas para a VML em complexo com o antÃgeno Tn e GalNAc foram determinadas com resoluÃÃes de 1.4 e 1.7 Ã, respectivamente. A maioria das lectinas obtidas a partir de fontes naturais consiste em misturas de diferentes isoformas, uma caracterÃstica indesejada para aplicaÃÃes biomÃdicas. Com base nisso, uma construÃÃo recombinante para VML (rVML) foi expressa em Escherichia coli, sendo obtida de forma solÃvel em com alto rendimento. A estrutura cristalina para a rVML, bem como para seus complexos com o antÃgeno Tn, GalNAc e α-Lactose foram determinadas com resoluÃÃes de 1.7, 2.7, 2 e 1.8 Ã, respectivamente, apresentando a mesma estrutura geral e padrÃes de interaÃÃo que a lectina silvestre. Com o intuito de gerar um perfil comparativo entre a VML e outras lectinas de leguminosas capazes de reconhecer o antÃgeno Tn, foram realizadas anÃlises de docking molecular utilizando fragmentos de O-mucinas diferentemente decorados com o antÃgeno Tn. Esse perfil ressalta como alteraÃÃes sutis no elenco ou disposiÃÃo dos aminoÃcidos constituintes do sÃtio de ligaÃÃo a carboidrato, que talvez nÃo influenciem a capacidade de ligaÃÃo a monossacarÃdeo, podem impactar diretamente a habilidade dessas lectinas em reconhecer antÃgenos em condiÃÃes naturais. Adicionalmente aos jà caracterizados efeitos biolÃgicos relatados para VML, a similaridade entre sua estrutura e perfis de interaÃÃes quando comparadas a outras lectinas comumente utilizadas como marcadores histoquÃmicos (e.g., VVLB4 e SBA), sugerem fortemente a possÃvel utilizaÃÃo da VML como uma nova ferramenta na pesquisa do cÃncer. Esse trabalho consiste no primeiro relato de estruturas cristalogrÃficas para uma lectina de leguminosa especÃfica para Gal/GalNAc da tribo Dalbergieae.
Lectins are a very diverse class of proteins able to bind specific sugar structures reversibly and with high specificity, but without enzymatically modifying them, triggering several important cellular processes. Among the different lectin families, legume lectins are the most thoroughly studied and have been widely reported to exhibit a number of links to many pathological processes, including carcinogenesis. The remarkable anti-tumor properties of some legume lectins, resulting from their ability to induce programmed cell death and/or autophagocytosis in cancer cells have attracted much attention for biomedical applications. Moreover, a few galactose/N-acetylgalactosamine (Gal/GalNAc)-binding lectins from this group have proven to be useful markers for cancer histochemistry, and the structural characterization of these lectins bound to specific cancer epitopes has been carried out successfully. The seed lectin isolated from the legume tree Vatairea macrocarpa (VML) is a well characterized Gal/GalNAc-binding protein able to specifically recognize naturally occurring O-mucins presenting the carcinoma epitope Tn antigen (GalNAc-α-O-Ser). The crystal structures of VML in complex with Tn antigen and GalNAc have been determined at the resolution of 1.4 and 1.7 Ã, respectively. Unfortunately, most of lectins obtained from natural sources consist in a mixture of forms, which is an undesired feature for biomedical applications. Thus, the recombinant form of VML (rVML) was expressed in Escherichia coli, being obtained soluble and wih high yielding. The crystal structure for rVML, as well as for the complex with Tn antigen, GalNAc and α-Lactose have been determined at resolutions of 1.7, 2.7, 2 and 1.8 Ã, respectively, presenting the same overall structure and binding patterns as the wild lectin. Molecular docking analysis of this new structure and other Tn-binding legume lectins to O-mucin fragments differently decorated with this antigen provides a comparative binding profile among these proteins, stressing that subtle alterations that may not influence monosaccharide binding can, nonetheless, directly impact the ability of these lectins to recognize naturally occurring antigens. In addition to the specific biological effects of VML, the structural and binding similarities between it and other lectins commonly used as histological markers (e.g., VVLB4 and SBA) strongly suggest that VML can be used as a new tool for cancer research. This is the first report of crystal structures of a Gal/GalNAc-binding legume lectin from the Dalbergieae tribe.
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Howgego, Joshua David. "Synthetic lectins with novel selectivity". Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.573385.
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Carbohydrates are the most plentiful organic molecules on the surface of the earth and also some of the most complex. They are not just fuel sources, but also function as identifying markers for cells, on the surfaces of which they reside in the form of glycoconjugates. These identifying molecules are recognised by lectins; proteins which bind carbohydrates through non-covalent interactions. This recognition mediates a whole range of important biological processes, from fertilisation to infection with pathogens. 'Synthetic lectins' in the context of this thesis are artificially designed and synthesised organic receptor molecules. They bind sugars in aqueous environments through non-covalent interactions and as such may be considered biomimetic in the strictest sense. Synthetic lectins designed according to the 'temple' principles developed in the Davis group have so far been successful in binding sugars which have all their hydroxyl groups orientated equatorially, such as glucose. In this thesis the problem of how to design synthetic lectins for monosaccharides with less uniform distribution of functionality (for example mannose or galactose) is explored. To that end the synthesis of receptors 1 - 3 is described. Characterisation of the binding behaviour of these molecules reveals new patterns of selectivity; for example, disaccharides are bound in preference to monosaccharides. Receptor 4 shows a small but significant affinity for N-acetylneuraminic acid. This substrate is of widespread importance in physiological signalling, and few artificial receptors have previously bound this substrate in water through purely non-covalent interactions.
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Peron, Gabriela. "Tabhys: um peptídeo com atividade lectínica extraído de Tabernaemontana hystrix". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/17/17147/tde-11112015-155331/.
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Lectinas são proteínas que possuem pelo menos um domínio não catalítico que se liga reversível e especificamente a um monossacarídeo ou oligossacarídeo. A capacidade de ligação a diferentes tipos de açúcares torna essas moléculas ferramentas úteis no estudo de diversos processos celulares específicos. Embora as lectinas de plantas sejam amplamente estudadas, aquelas referentes à família Apocynaceae ainda são pouco exploradas. Resultados prévios obtidos pelo nosso grupo de pesquisa mostraram que extratos brutos de súber do caule da apocinácea Tabernaemontana hystrix Steud apresenta atividade hemaglutinante. Além de aglutinar eritrócitos do sistema ABO, a putativa aglutinina foi capaz de estimular a síntese de RNAm de IL-6 e TGF- beta em células esplênicas de camundongos. À vista disso, no presente projeto tivemos como objetivo identificar, caracterizar bioquimicamente e avaliar o possível potencial imunoestimulador da aglutinina de T. hystrix. Os extratos de T. hystrix obtidos por meio da farinha de raspas do súber apresentaram atividade hemaglutinante, o que não foi observado no extrato do caule destituído de súber e no extraído das folhas. Para comprovar que se tratava da atividade observada anteriormente, obtivemos a inibição da hemaglutinação com a glicoproteína fetuína, mas não houve inibição por monossacarídeos. Foi determinado um protocolo de isolamento da hemaglutinina com precipitação do extrato do súber com sulfato de amônio, cuja atividade foi recuperada no material precipitado na faixa de 30 a 60% de saturação, seguido de cromatografias sequenciais por (1) interação hidrofóbica (HiTrap Octyl), (2) troca catiônica (HiTrap SP), (3) fase reversa (EC Nucleosil C18) e (4) afinidade (Blue Sepharose). Nessas colunas a atividade foi recuperada do (1) material não retido e dos eluatos (2 e 4) com 1M e 0,5M de NaCl, respectivamente, e (3) 83% de acetonitrila. Esse protocolo produziu uma preparação homogênea contendo um peptídeo cuja análise eletrofóretica revelou massa molecular (MM) aproximada de 3kDa e concentração hemaglutinante mínima de 50g/mL. A fim de determinar se esse peptídeo formava estrutura quaternária (dímeros, tetrâmetros, etc.), característica da maioria das lectinas de plantas, submeteu-se a preparação a uma eletroforese em gel nativo (PAGE), não sendo observadas mudanças na MM do peptídeo e nem a presença de outras moléculas com MM maiores que pudessem estar associadas a ele, o que sugere que a aglutinina de T. hystrix (denominado aqui de Tabhys) é um peptídeo de MM aproximada de 3kDa. O fato da heveína, um dos peptídeos lectínicos com atividade antifúngica mais estudado, ter especificidade por quitina nos motivou a tentar o isolamento do peptídeo em coluna desse polissacarídeo. Observou-se atividade hemaglutinante e presença de peptídeo com MM de 3kDa no material eluído com Ácido acético a 0,1M da coluna de quitina. Curiosamente, nenhuma de nossas preparações foram capazes de inibir o crescimento do fungo Trichophyton rubrum. O peptídeo purificado foi testado quanto a sua capacidade em induzir a proliferação celular e a produção de citocinas em células esplênicas murinas. Os resultados dos ensaios de RT-PCR em tempo real e citometria de fluxo demonstraram que o a aglutinina de T. hystrix não foi capaz de estimular a proliferação de linfócitos, entretanto, induziu o aumento de mensagem para a citocina TGF-beta, cujo pico de produção ocorreu em célula estimuladas com 37ng/mL. Neste estudo, relatamos a presença de um peptídeo no extrato de T. hystrix com atividade hemaglutinante, o que é relativamente raro e novo. Devido a isso, este estudo pode proporcionar novas perspectivas e paradigmas nos estudos das lectinas a nível molecular e estrutural.Lectins are proteins that have at least one non-catalytic domain that binds specifically and reversibly to a monosaccharide or oligosaccharide. This ability to bind to different types of sugars makes these molecules useful tools in the study of various specific cellular processes. Although the plant lectins are widely studied, those belong to Apocynaceae family are still little explored. Previous results obtained by our research group showed that bark crude extracts from Tabernaemontana hystrix Steud (Apocynaceae) had hemagglutination activity. Besides to agglutinate erythrocytes from ABO blood group system, the putative agglutinin induced the synthesis of IL-6 and TGF-beta mRNA in mouse spleen cells. Here we aim to identify, characterize biochemically and evaluate the possible immunostimulatory potential of T. hystrix agglutinin. The haemagglutination activity was obtained from crude extracts of bark flour, but not of flours of stems without bark and leaves. The activity of the bark extract was similar to that from the previous study, since the haemagglutination was inhibited by the glycoprotein fetuin, but not by monosaccharides. An isolation protocol was determined by using ammonium sulfate precipitation, with haemagglutination activity recovered in the range of 30-60% of saturation, and sequential chromatography procedures: (1) hydrophobic interaction (HiTrap Octyl), (2) cation-exchange (HiTrap SP), (3) reverse phase (EC Nucleosil) and (4) affinity (BlueSepharose) chromatography. From these columns the activity was recovered in the (1) unbound material, and eluates (2 and 4) with 1M and 0,5M of NaCl, respectively, and (3) 83% acetonitrile. On the basis of electrophoresis analysis, the protocol produced a preparation comprised of only band corresponding a peptide with molecular weight (MW) of about 3-kDa, with minimum haemagglutination concentration of 50g/ml. To determine if this molecule arrangement had a quaternary structure arrangement, a feature of most known lectins, we submitted the preparation to a native electrophoresis. Because there was neither change in migration pattern nor presence of molecules of higher molecular mass, we suggested that T. hystrix peptide (Tabhys) is a peptide with MW of about 3-kDa. Since hevein, which is a most studied lectin-like peptide with antifungal activity, binds specifically to chitin, we performed an affinity chromatography in the chitin column with bark extract. We observed haemagglutination activity and the presence of peptide with MW of 3-kDa in the material bound to column and eluted with 0,1M acetic acid. Curiously, this peptide was not able to inhibit the growth of the fungus Trichophyton rubrum. Thereafter, when the purified peptide was used to stimulate murine spleen cells, we detected the expression of TGF-beta message, with a peak production obtained in cell stimulated with 37 ng/mL of Tabhys. In the current study, we isolated a peptide from crude extract of T. hystrix bark with haemagglutination activity, providing new perspectives in molecular and structural researches of peptide lectins.
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Didak, Blanka. "Synthèse de néoglycoconjugués et dendrimères glycomimétiques utilisés pour le développement de puces à lectines de type C et leur validation". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAV036.
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Les lectines de type-C (CLR) sont des protéines de liaison au glycane qui reconnaissent les sucres de manière dépendante du Ca2+. Ils ont des rôles divers dans l'organisme humain. Ils sont responsables des interactions et de l'internalisation d'agents pathogènes tels que Candida albicans, Mycobacterium tuberculosis, le VIH ou le virus Ebola. Ils sont également impliqués dans le développement ou la prévention du cancer par la reconnaissance de glycanes spécifiques exprimés à la surface des cellules tumorales.L'importance cruciale est de trouver des ligands pour les CLR qui induiront une réponse immunitaire ou des inhibiteurs pour les lectines impliquées dans la promotion des infections dans l'organisme. L'objectif du réseau IMMUNOSHAPE était d'examiner de près les rôles, les spécificités et les différences entre les CLR et d'essayer de trouver des molécules appropriées pour stimuler la réponse immunitaire. Au cours de cette thèse, les néoglycoprotéines (NGP) contenant des glycodendrons de différentes valences ont été synthétisées. Pour la synthèse ont été utilisés BSA et OVA comme porteurs de protéines sur lesquels sont couplés des composés monovalents et des dendrons avec αMan et Manα1-2Man de trois et neuf valences. Tous les NGP ont été synthétisés par la chimie click avec deux équivalents de glycodendron / BSA. De plus, des NGP avec des glycomimétiques sur la base de fucose et de Manα1-2Man ont été préparés.L'affinité des molécules synthétisées a été analysée avec GLYcoPROFILE, la plateforme technologique développée par GLYcoDiag dans le but de mieux étudier les interactions glycobiologiques. Il a été évalué que tous les composés testés présentaient un effet multivalent fort sur quatre lectines spécifiques du mannose, y compris deux CLR : DC-SIGN et Langerin. La néoglycoprotéine avec 11 dendrons Manaαl-2 Man nonavalés a obtenu la meilleure avidité pour toutes les lectines testées. Les IC50 obtenues pour la Langerine et le DC-SIGN sont respectivement de l’ordre du nanomolaire et picomolaire, c’est une des valeurs les plus faibles obtenues pour ces deux lectines.L'étude des interactions glycobiologiques a été élargie par l'analyse des différences entre les glycanes avec les liaisons O, C et S et leurs interactions avec les lectines. Il a été observé que les C-glycanes n'ont pas le même mode de liaison que les O-glycanes et, par la suite, ne présentent pas le même effet multivalent attendu, que les O-glycanes. Dans le contexte des glycosides, nous montrons que l’O-glucoside présente de meilleures interactions avec les lectines purifiées que le S-glucoside, tandis que le S-galactoside offre une inhibition significativement meilleure entre les kératinocytes humains normaux et les néoglycoprotéines correspondantes. En outre, une étude intéressante a porté sur les interactions entre les thio-sialosides et la sialidase NanA. Cette analyse a montré que la multivalence a un effet important non seulement sur la lectine, mais également sur la liaison de l’enzyme. Les NGP synthétiques thio-sialylés ont mis en évidence un inhibiteur multivalent efficace de l'enzyme NanA.Au final, cette thèse présente des résultats intéressants sur l'influence significative des composés multivalents sur les interactions glycobiologiques entre les glycanes et les lectines ainsi que sur les enzymes. Cette connaissance pourrait être utilisée dans la conception future des vaccins et de leurs adjuvants pour le traitement des infections,du cancer et, en général, pour la formation de la réponse immunitaireC-type lectins (CLRs) are glycan binding proteins which recognize sugars in Ca2+ dependent manner. They have diverse roles in human organism. They are responsible for interactions and internalization of pathogens like Candida albicans, Mycobacterium tuberculosis, HIV or Ebola virus. They are also involved in development or prevention of cancer through recognition of specific glycans expressed on surface of tumor cells.The crucial importance is to find ligands for CLRs which will induce immune response or inhibitors for lectins which are involved in promotion of infections in organism. The goal of IMMUNOSHAPE network was to closely examine roles, specificities and differences between CLRs and try to find appropriate molecules for driving immune response. During this thesis, neoglycoproteins (NGPs) containing glycodendrons with different valences were synthetized. For synthesis were used BSA and OVA as protein carriers on which are coupled monovalent compounds and dendrons with αMan and Manα1-2Man in three and nine valences. All NGPs were synthetized with click chemistry with two ratios of glycodendron/BSA. Additionally, NGPs with glycomimetics on the basis of fucose and Manα1-2Man were prepared.The affinity of synthetized molecules was analyzed with GLYcoPROFILE, technology platform developed in GLYcoDiag with the aim of better and more precise investigation of glycobiological interactions. It was evaluated that all tested compounds showed strong multivalent effect on four mannose specific lectins, including two CLRs: DC-SIGN and Langerin. Neoglycoprotein with 11 nonavalent Manα1-2Man dendrons achieved the best avidity for all tested lectins. Obtained IC50 for Langerin and DC-SIGN are of nanomolar and picomolar range respectively, which are one of the lowest values obtained for these two lectins.Studying glycobiological interactions was expanded by analysis of differences between glycans with O-, C- and S-linkage and their interactions with lectins. It was observed that C-glycans does not have the same mode of binding like O-glycans and subsequently, do not show the same expected multivalent effect such as O-glycans. In the context of glycosides, we show that even O-glucoside achieved slithly better interactions with purified lectins in comparison with S-glucoside, S-galactoside provide significantly better inhibition between normal human keratinocytes and corresponding neoglycoproteins in comparison with O-galactoside. Furthermore, interesting study was investigation of interactions between thio-sialosides and sialidase NanA. This analysis showed that multivalency has a strong effect not only on lectin, but also on enzyme binding. Synthetized thio-sialylated NGPs showed as efficient, multivalent inhibitor of NanA enzyme.Altogether, this thesis presents interesting results of significant influence of multivalent compounds on glycobiological interactions between glycans and lectins as well as enzymes. This knowledge could be used in future design of vaccines and their adjuvants for infection and cancer treatment and in general, for shaping immune response
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Murarasu, Thomas. "The Shiga Toxin B-Subunit : a Promising Scaffold for the Targeting of Tumor Specific Glycosphingolipids". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS512.
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Le cancer représente la second cause de décès au monde. Le développement de traitements innovants contre le cancer repose aujourd’hui sur l’identification de biomarqueurs des tumeurs et le développement de produits thérapeutiques capables de reconnaitre ces marqueurs de façon spécifique. Ces produits thérapeutiques de nouvelles générations ont le potentiel d’éliminer spécifiquement les cellules tumorales et donc de réduire les effets secondaires des traitements ainsi que les risques de rechute. Malheureusement, un certain nombre de patients ne peuvent bénéficier de ces traitements, du fait de l’absence de biomarqueurs connus à la surface de leur tumeur. Ce projet a ainsi pour ambition de développer de nouvelles thérapies ciblées en exploitant une nouvelle classe de biomarqueurs et ainsi de venir enrichir l’arsenal thérapeutique disponible pour le traitement des cancersCancer is the second cause of death worldwide. Recent advance in cancer treatments involved the identification of cancer biomarkers and the development of efficient therapeutic products able to specifically recognize them. This new class of products has the ability to specifically target tumor cells, with the major advantages to decrease or abolish treatments side effects and relapses of the disease. Unfortunately, a certain number of patients do not respond to those treatments lacking the expression of those biomarkers on their tumor. This project aims at developing new targeted therapies by exploiting a new class of cancer biomarkers, which would potentially extend the therapeutics options against cancer
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Coelho, Mirela Batista. "Estudo da atividade inseticida e pro-inflamatoria da lectina isolada de sementes de 'Annona coriacea' Mart". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314522.
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Orientador: Maria Ligia Rodrigues MacedoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: As lectinas são um grupo de proteínas e/ou glicoproteínas que se ligam específica e reversivelmente a carboidratos. Estudos têm demonstrado que essas proteínas possuem importantes atividades biológicas como atividade inseticida contra insetos e respostas imunológicas e fisiológicas em animais. Neste trabalho, tivemos como objetivos comparar os efeitos da lectina de sementes de Annona coriacea (ACLEC), com massa molecular de aproximadamente 14 kDa, sobre o desenvolvimento dos lepidopteras Anagasta kuehniella e Corcyra cephalonica assim como o estudo dos índices nutricionais desses insetos, e investigar a habilidade dessa lectina em induzir a migração de leucócitos em camundongos e os mecanismos farmacológicos delineadores desse processo, utilizando peritonite como modelo experimental. Os resultados da atividade inseticida de ACLEC mostraram que a lectina não produziu efeitos significativos sobre a sobrevivência e o peso larval de Corcyra cephalonica alimentada em dieta contendo até 2,0% de ACLEC, porém, para Anagasta kuehniella, em uma dieta artificial contendo 1,5% e 1,0% de ACLEC produziu um LD50 e WD50, respectivamente. Os resultados dos experimentos do consumo alimentar dos insetos apresentaram apenas uma redução na eficiência de conversão do alimento ingerido (ECI) e do alimento digerido (ECD) em larvas de A. kuehniela. A presença de ACLEC (2,0%) na dieta alimentar em ambos os insetos não modificou a digestibilidade aproximada (AD), mas promoveu um aumento no custo metabólico (CM) e um aumento da atividade proteolítica nas fezes do lepidóptero A. kuehniella. Este mecanismo pode promover uma modificação no meio ambiente da membrana e consequente disrupção do mecanismo de reciclagem ede enzimas, idicando a possibilidade de utulizar esta lectinas como uma estratégia biotecnológica para o manejo de insetos. Para a análise da atividade proinflamatória de ACLEC, camundongos Swiss machos foram injetados intraperitonealmente com ACLEC (3-100 µg/cavidade), de 4 a 96 h e logo após a contagem de leucócitos no fuído do lavado peritoneal foi avaliado. ACLEC induziu uma acumulação de neutrófilos dose-dependente, alcançando a respsota máxima a 16 h após a injeção (aproximadamente um aumento de 40x para 30 µg/cavidade). Uma significante acumulação de células mononucleares foi observada a 72 h (aumento de 2,7x). O carboidrato manose aboliu o inlfuxo de neutrófilos, porém sacarose e glicose não tiveram efeito. Dexametasona, o inibidor de ciclooxigenase-2 celecoxibe e o antagonista do receptor PAF PCA4248 significantemente reduziram o influxo de neutrófilos induzido por ACLEC. O antagonista de taquicinina NK1 SR140333, o antagonista de taquicinina NK2 SR48968, o inibidor não seletivo de NO L-NAME, o inibidor seletivo de NOS Aminoguanidina e o inibidor de lipoxigenase AA861 todos falharam em modificar a resposta induzida por ACLEC. Em conclusão, ACLEC é capaz de atrair neutrófilos na cavidade peritoneal de camundongos por mecanismos envolvendo interações da lectinas com o reconhecimento específico de resíduos de manose presentes nas células, induzindo a liberação de mediadores derivados de COX-2 e PAF
Abstract: Lectins are a group of proteins and/or glycoproteins, which exhibit specific and reversible carbohydrate-binding activities. Studies have demonstrated that such proteins possess important biological activities including insecticide activity as well as immunological and physiological responses in animals. In this investigation, our aim was to compare the effects of lectin isolated of Annona coriacea (ACLEC) seeds, with a molecular mass of 14 kDa, on the development of Anagasta kuehiella and Corcyra cephalonica Lepidopteras, as well as the study of their nutritional index. Since plant lectins are known to present inflammatory activity, this study also sought to investigate the leukocyte migration induced by ACLEC, and inflammatory mediators involved in this phenomenon. The results of insecticide activity of ACLEC showed that the lectin did not produce significant effects on survival and weight of C. cephalonica on an artificial diet of 2,0% of ACLEC, however, for A. kuehniella,on an artificial diet containing 1.5% and 1.0% ACLEC, it produced a LD50 and WD50, respectively. The results from dietary utilization experiments carried out with caterpillars presented only a reduction in efficiency of conversion of ingested food (ECI) and digested food (ECD) in A. kuehniella. ACLEC in the diet did not modify the approximate digestibility (AD) of any insect, but an increase of CM (metabolic cost) and an increase of proteolytic activity in the faeces were observed in A. kuehniella. These results indicate that ACLEC possesses an insecticide effect only towards A. kuehniella larvae, possibly through the binding of lectin on chitin components of membrane peritrophic or glycosylated proteins in the insect midgut. This mechanism can promote a change in membrane environment with the consequent disruption of enzyme recycling mechanisms, indicating the possibility of using this lectin in a biotechnological strategy for insect management. To test proinflammatory activity of ACLEC, male Swiss mice were intraperitoneally injected with ACLEC (3-100 µg/cavity), and at 4 to 96 h thereafter the leukocyte counts in peritoneal washing fluid were evaluated. ACLEC induced a dose-dependent neutrophil accumulation, reaching maximal responses at 16 h after injection (approximately 40-fold increase for 30 µg/cavity). Significant accumulation of mononuclear cells was observed at 72 h (2.7-fold increase). The carbohydrate mannose nearly abolished the neutrophil influx, whereas sucrose and glucose had no effect. Dexamethasone, the cyclooxygenase-2 inhibitor celecoxib and the PAF receptor antagonist PCA4248 significantly reduced ACLEC-induced neutrophil influx. The tachykinin NK1 antagonist SR140333, the tachykinin NK2 antagonist SR48968, the non-selective NO inhibitor L-NAME, the selective inducible NOS inhibitor aminoguanidine and the lypoxygenase inhibitor AA861 all failed to modify the ACLEC-induced responses. In conclusion, ACLEC is able to attract neutrophils into the mice peritoneal cavity by mechanisms involving interactions of the lectin with cell-specific mannose recognition, leading to the release of COX-2-derived mediators and PAF
Doutorado
Bioquimica
Doutor em Biologia Funcional e Molecular
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Goto, Leandro Seiji. ""Estudos estruturais e funcionais sobre duas lectinas: cadeia B recombinante da pulchellina & Camptosemina"". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-29032007-121740/.
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Lectinas estão situadas dentro de um grupo estruturalmente diverso de proteínas que se ligam a carboidratos e glicoconjugados com grande especificidade. Encontradas em diversos organismos, elas são moléculas extremamente úteis na caracterização de sacarídeos, como agentes mediadores de endereçamento de fármacos ou até mesmo como marcadores de superfície celular. A pulchellina é uma glicoproteína heterodimérica ligante de D-Galactose oriunda de sementes de Abrus pulchellus e classificada como proteína inativadora de ribossomo do tipo 2 (type 2 ribosome-inactivating protein - type 2 RIP). A cadeia B recombinante da pulchellina (rPBC) foi previamente produzida em E. coli BL21(DE3). Neste presente trabalho, a rPBC é analisada quanto a sua atividade, interação com células de mamíferos in vitro e estabilidade estrutural. Os resultados indicam que a rPBC possui seletividade quanto a tipos celulares alvo e é endocitada ativamente, provavelmente compartilhando a via de endocitose descrita para outras RIPs. Além disto, a rPBC foi unida à cadeia catalítica e o heterodímero resultante demonstrou toxicidade similar à da holotoxina nativa, confirmando a atividade da rPBC e atribuindo-lhe papel essencial no mecanismo de intoxicação. Uma segunda parte deste trabalho tratou de outra lectina, extraída de sementes de Camptosema ellipticum. Recentemente, experimentos com extratos aquosos obtidos a partir de sementes de Camptosema ellipticum demonstraram possuir atividade hemaglutinante frente a hemácias humanas. Tal atividade foi atribuída a um dado componente protéico que foi então purificado através de cromatografias de troca iônica e exclusão molecular. A proteína, então chamada camptosemina, demonstrou ocorrer na forma de um tetrâmero e cujo estado de oligomerização pode ser controlado pelo pH do meio. Informações sobre a seqüência primária na porção amino-terminal, obtidas por seqüenciamento de aminoácidos, permitiram o desenho de oligonucleotídeos degenerados para a amplificação e clonagem de seu cDNA. As seqüências dos clones obtidos foram submetidas a diversas rotinas de procura de dados do NCBI. Entre os resultados retornados encontraram-se a concanavalina e a aglutinina de amendoim, dois representantes da chamada família de lectinas de leguminosas. Representantes deste grupo compartilham com a camptosemina o tamanho de seus monômeros e a forma de controle de seus graus de oligomerização. O presente trabalho traz a caracterização preliminar da camptosemina quanto a sua seqüência primária e oligomerização através de técnicas de clonagem e de espectroscopia. Foi possível a clonagem de duas variantes para o cDNA da camptosemina cujas seqüências prevêem um peptídeo sinal N-terminal ausente na proteína madura. As seqüências primárias deduzidas são muito semelhantes entre si e em comparação com outros membros da família de lectinas de leguminosas. A camptosemina se demonstrou extremamente resistente a mudanças de temperatura, exibindo sua dissociação em monômeros somente sob pHs extremamente ácidos ou alcalinos.Lectins have been placed in a structurally diverse group of proteins that bind carbohydrates and glycoconjugates with high specificity. Found in several organisms, they are extremely useful molecules in the characterization of saccharides, as drug delivery mediators, and even as cellular surface markers. Pulchellin is a D-Galactose-binding heterodimeric glycoprotein from Abrus pulchellus seeds and classified as a type-2 ribosome-inactivating protein (type-2 RIP). The recombinant pulchellin B (rPBC) was previously produced in E. coli BL21 (DE3). In the present work, rPBC is analyzed with respect to its interaction with mammal cells in vitro and structural stability. Results show that rPBC has selectivity for targeted cell types and that it is actively endocytosed, probably by the same route described for other RIPs. Furthermore, rPBC was bond to the catalytic chain and the resulting heterodimer has shown toxicity degree very similar to the native holotoxin, confirming rPBC activity and attributing it a essential role in the intoxication mechanism. A second part of this work has dealed with another lectin extracted from the seeds of Camptosema ellipticum. Recently, experiments with water-soluble extracts obtained from the seed of Camptosema ellipticum have shown to have hemagglutinative properties when assayed with human erythrocytes. Such biological activity was attributed to a certain proteic component that was purified by ion-exchange and size-exclusion chromatographies. The protein, so called camptosemin, has shown to occur as a tetramer and which oligomerizations state could be driven by the environmental pH. Primary sequence information from the amino-terminal portion, obtained by aminoacid sequencing, allowed the design of degenerated oligonucleotides for the amplification and cloning of its cDNA. The obtained clones sequences were submitted to several NCBI data bank search scripts. Among the retrieved results were found concanavalin and peanut agglutinin, two representatives of the called legume lectins family. Members of this group share with camptosemin their monomer sizes and the way their oligomerization state can be driven. This present work characterizes camptosemin with respect to its sequence and oligomerization using cloning and spectroscopy techniques. It was possible the cloning of two cDNA variants for camptosemin which sequences deduce an N-terminal signal peptide absent in the mature protein. Deduced primary sequences are very similar to each other and to other legume lectin members. Camptosemin has shown being extremely temperature resistant, only dissociating in monomeric subunits under extremely acid or alkaline pHs.
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de, Oliveira Jose T. A. "Seed lectins : the effects of dietary Phaseolus vulgaris lectins on the general metabolism of monogastric animals". Thesis, University of Aberdeen, 1986. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU367276.
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Rats, mice, pigs, quails, chickens, steers and even some insects are unable to grow properly and in some cases die when fed on diets containing raw kidney bean (Phaseolus vulgaris). Although this problem has been extensively studied the precise mechanism of the interference of dietary antinutritional factors with the growth and health of these animals or insects is still not completely understood. In the present work, the toxic effects of the purified kidney bean globulin lectins upon the general metabolism of the rats were studied. The results of the experiments indicated that both qualitatively and quantitatively most of the deleterious effects of raw kidney bean feeding to rats could be accounted for by the inclusion of the pure lectin into nutritionally adequate semi-synthetic diets based on high-quality proteins such as egg albumin. These effects included: (a) a drastic depletion of storage lipid and glycogen and loss of body protein. (The rate of the catabolism of lipids was considerably higher than that of any other body constituent.); (b) a large loss of skeletal muscle (indicated by the change of muscle mass and atrophy of gastrocnemius and plantaris muscles); (c) enlargement of the small intestine, liver and pancreas and involution of the thymus; (d) increased excretion of faecal and urinary nitrogen with a consequently poor nitrogen retention; (e) increased 3-hydroxybutyrate output, and (f) changes in blood concentrations of pancreatic hormones. The magnitude of most of these effects was dependent upon the dietary concentrations of kidney bean globulin lectins (PHA). Thus the extent of the depletion of body lipid and glycogen, loss of muscle, enlargement of the small intestine, liver and pancreas, the extent of the thymus atrophy as well as the increased faecal and urinary nitrogen and increased urinary 3-hydroxybutyrate outputs were shown to be directly correlated with the dietary PHA concentration. In contrast to the deleterious effects of fully active, native PHA, the aggregated lectin preparation (UPHA) did not cause any significant antinutritional effects. The overall results indicated that raw kidney bean is toxic mainly because of its lectin constituent and that local (gut) and systemic adverse reactions caused by PHA account for most of the deleterious effects of this potentially important source of dietary protein for animals and humans.
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Odom-Crespo, Eric William. "F-type lectins biochemical, genetic, and topological characterization of a novel lectin family in lower vertebrates /". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1437.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Marine-Estuarine-Environmental Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Lu, Jinhua. "Mammalian lectins containing collagen-like domains". Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303657.
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Gupta, G. "Artificial lectins : biomimetic ligands for glycoproteins". Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599789.
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This thesis describes the rational design and synthesis of selective and sterilisable biomimetic ligands for the resolution of glycosylated and carbohydrate depleted protein forms. Based on the principles of natural carbohydrate recognition, a putative library of 196 glycoprotein-binding ligands was designed and synthesised by solid phase combinatorial approaches. A preparative affinity chromatography screening assay against a well-characterised complex-type model glycoprotein, helped identify a triazine-based acyclic immobilised ligand 11/11, comprising bis-benzylamine substituents as the 'lead' ligand. The carbohydrate recognising potential of the 'lead' ligand was revealed by reduced binding of periodate oxidised model glycoprotein, and by 'sharp' elution profiles achieved with borate buffer eluents. Specific elution and competitive binding experiments of bound glycoprotein against free sugars showed that the monosaccharide specificity of the immobilised ligand was in the order mannoside>glucoside>galactoside. The ability of immobilised ligand 11/11 to bind several well-characterised oligomannose-, complex- and hybrid-type glycoproteins, and quantitatively elute them with mannoside confirmed its hexose sugar selectivity. Resolution of protein glycoforms was demonstrated by the ability of immobilised ligand 11/11 to retain and selectively elute the glycosylated form of an oligomannose-type protein, whilst the carbohydrate deficient counterpart bound non-specifically and irreversibly to the ligand. The structural integrity of immobilised ligand 11/11 was established by a semi-solution synthetic strategy, whereby the intermediate products were characterised by TLC, 1H-NMR and MS. This work has demonstrated the development of a diastereo-selective, sterilisable, stable and regulatory authority compliant biomimetic ligand, capable of resolving protein glycoforms.
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Sampaio, Alexandre Holanda. "Lectins from Ulva and Ptilota species". Thesis, University of Portsmouth, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310389.
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SILVA, Flávio de Oliveira. "Atividade moduladora da lectina isolada das sementes de Canavalia brasiliensis". Universidade Federal Rural de Pernambuco, 2012. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4585.
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Lectins are proteins that bind specifically and reversibly to carbohydrates, showing several biological effects. In this work, we carried out a literature review about biological effects of lectin extracted from seeds of Canavalia brasiliensis (ConBr), a plant present in the northeastern and southern Brazil, which is popularly known as wild bean of Ceará. In addition, we carried out a study to analyze the modulating activity of ConBr on murine splenocytes, verifying its effect on cell viability and proliferation, cytokine and nitric oxide (NO) production. We have also performed a study to evaluate ConBr effect on B16F10 murine melanoma cells by analyzing the inhibition of cell proliferation and migration as well as apoptosis induction and synthesis of cytokines and NO. The results show that ConBr induced at concentrations of 2.5, 5.0 and 10 μg/ml promoted the proliferation of splenocytes, with high cell viability. Furthermore, the concentration of 10 μg/ml induced cytokine production and nitric oxide on B16F10 murine melanoma, it was observed that ConBr inhibited tumor cell proliferation inducing apoptosis. It was also observed nitric oxide and IL-12 production by B16F10 cells under stimulus. ConBr lectin possesses a biotechnological potential use as a mitogen and anti-tumor agent.
As lectinas são proteínas que apresentam a capacidade de se ligar de maneira específica e reversível a carboidratos, exibindo distintos efeitos biológicos. Neste trabalho, realizou-se uma revisão de literatura sobre os efeitos biológicos da lectina extraída das sementes da Canavalia brasiliensis (ConBr), uma planta presente no Nordeste e Sul do Brasil, que é conhecida popularmente como feijão bravo do Ceará. Além disso, realizou-se um estudo para analisar a atividade moduladora da ConBr sobre esplenócitos murinos, verificando-se sua ação sobre a proliferação e viabilidade celular, produção de citocinas e óxido nítrico (NO). Realizou-se também, um estudo para avaliar o efeito da ConBr sobre células B16F10 de melanoma murino, analisando-se a inibição da proliferação e migração celular, bem como a indução de apoptose e síntese de citocinas e NO. Os resultados demostraram que a ConBr induziu nas concentrações de 2.5, 5.0 e 10 μg/ml promoveu a proliferação de esplenócitos, com alto índice de viabilidade celular. Além disso, a concentração de 10 μg/ml induziu a produção de citocinas e óxido nítrico. Em células B16F10 de melanoma murino, observou-se que a ConBr inibiu a proliferação das células tumorais promovendo apoptose celular. Verificou-se ainda, a produção de óxido nítrico e da citocina IL-12 pelas células submetidas ao estímulo. A lectina ConBr possue um potencial uso biotecnológico como mitógeno e agente antitumoral.
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JÃnior, Francisco Nascimento Pereira. "PurificaÃÃo, caracterizaÃÃo parcial e cristalizaÃÃo de uma lectina ligante de manose das sementes de Platymiscium floribundum Vogel". Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5882.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorAs sementes de Platymiscium floribundum Vogel, uma espÃcie pertencente à famÃlia Leguminosae, subfamÃlia Papilionoideae, tribo Dalbergieae, possuem uma lectina manose/N-acetil-D-glicosamina especÃfica, que aglutina eritrÃcitos nativos ou tratados com enzimas proteolÃticas de coelho. A lectina de sementes de P. floribundum foi purificada por precipitaÃÃo com sulfato de amÃnio seguida por cromatografia de afinidade em matriz de Sepharose-manose. Esse procedimento resultou na lectina purificada, nomeada de PFL. O processo de purificaÃÃo da PFL foi monitorado por SDS-PAGE e atividade hemaglutinante especÃfica, observou-se que a lectina purificada à caracterizada por um perfil eletroforÃtico composto por uma Ãnica banda, com massa molecular aparente de aproximadamente 29 kDa, tanto na presenÃa quanto na ausÃncia de um agente redutor. A anÃlise por espectrometria de massa indicou que PFL possui massa molecular de 27.054  2 Da, e teve sua estrutura primaria parcialmente sequenciada atravÃs de espectrometria de massa sequencial. PFL à uma glicoproteÃna e demonstra elevada estabilidade, sendo capaz de manter sua atividade hemaglutinante apÃs exposiÃÃo a temperaturas de atà 60  C por 1 hora e na faixa de pH de 7,0 a 9,0. A PFL nÃo apresentou atividade anti-inflamatÃria.em modelo de edema de pata. PFL foi cristalizada em diferentes condiÃÃes de cristalizaÃÃo.
Platymiscium floribundum Vogel seeds, a species of the Leguminosae family, Papilionoideae subfamily, Dalbergieae tribe, have a lectin mannose/N-acetyl-D-glucosamine specific rabbit erythrocytes that agglutinate native or treated with proteolytic enzymes. The lectin from P. floribundum was purified by precipitation with ammonium sulfate followed by affinity chromatography on Sepharose-mannose. This procedure resulted in a purified lectin, named PFL. PFL purification process was monitored by SDS-PAGE and showed that the purified lectin is characterized by an electrophoretic profile consists of a single band with apparent molecular mass of approximately 29 kDa, in both presence and absence of an reducer agent. The analysis by mass spectrometry indicated that PFL has a molecular mass of 27,054 Da, and its primary structure was partially sequenced. PFL is a glycoprotein and shows high stability, being able to maintain its haemagglutinating activity after exposure to temperatures up to 60 ÂC for one hour and at pH 7.0 to 9.0. The PFL showed no anti-inflammatory activity in paw edema model. PFL was crystallized under different crystallization.
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Landim, PatrÃcia Gadelha de Castro. "Xiloglucanas e galactomananas de leguminosas: interaÃÃo com lectinas D-galactose-ligantes". Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8583.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoPolissacarÃdeos ocorrem em grandes quantidades nas sementes como componentes da parede celular ou como reserva. Dentre estes Ãltimos, incluem-se as xiloglucanas cotiledonÃrias e as galactomananas endospÃrmicas. As xiloglucanas apresentam uma cadeia principal de β-D-(1→4)-glucana ramificada com ligaÃÃes α-(1→6) por resÃduos D-xilopiranosÃdeos ou β-D-galactopiranosÃdeo-(1→2)-D-xilopiranosÃdeos, enquanto as galactomananas endospÃrmicas consistem em cadeias polimÃricas de resÃduos β-D-manopiranosil (1→4) ligados, substituÃdos em O-6 por unidades de α-D-galactopiranosil. O objetivo deste trabalho foi analisar a interaÃÃo de xiloglucanas e galactomananas com lectinas galactose-ligantes e, assim, sugerir o uso de tais polissacarÃdeos como alternativa barata e eficaz na preparaÃÃo de matrizes cromatogrÃficas para o isolamento e determinaÃÃo da especificidade anomÃrica de novas lectinas. Dessa forma, as interaÃÃes das lectinas das sementes de Artocarpus integrifolia (frutalina), Artocarpus incisa (jacalina), Ricinus communis (ricina) e Arachis hypogaea (PNA) com matrizes de xiloglucanas de sementes de Copaifera langsdorffii, Mucuna sloanei e Hymenaea courbaril (MC, MMu, MJ, respectivamente) e de galactomananas de Mimosa scabrella, Stryphnodendron barbatiman, Adenanthera pavonina e Dimorphandra mollis (MM, MS, MA; MD, respectivamente) foram analisadas. As galactomananas apresentaram melhor capacidade de retenÃÃo da jacalina (MA â 0,92 mg ; MM â 1,48 mg ; MD â0,88 mg ; MS â 0,83 mg) e da frutalina (MA â 0,99 mg ; MM â 1,09 mg ; MD â 0,94 mg ; MS â 0,85 mg), lectinas que possuem especificidade por α-D-galactose. Vale destacar que a galactomanana de M. scabrella apresentou melhor capacidade de retenÃÃo da lectinas testadas. Por outro lado a ricina, capaz de ligar-se aos dois anÃmeros, mas que se liga preferencialmente ao anÃmero β, teve maior massa retida nas colunas de xiloglucana (MMu â 2,17 mg ;MJ â 1,30 mg; MC â 2,83 mg). Houve diferenÃa nos perfis de retenÃÃo da PNA, que tambÃm se liga aos anÃmeros α e β da galactose, sendo que a melhor retenÃÃo foi na coluna contendo matriz de M. sloanei (0,12 mg). As colunas foram todas saturadas com extrato bruto a partir das farinhas das sementes, para que se utilizasse a capacidade mÃxima de retenÃÃo de cada matriz. Atividade hemaglutinante foi detectada em ambos os picos PI e PII. Para a ricina, atividade tÃxica foi realizada e detectada para todos os PII obtidos. Por meio de SDS-PAGE, a pureza de cada uma das lectinas foi confirmada. Diante dos resultados expostos, pode-se sugerir o uso de xiloglucanas e galactomananas para o isolamento, purificaÃÃo e determinaÃÃo da especificidade anomÃrica de lectinas galactose-ligantes.
Polysaccharides are found in large quantity in seeds and they represent the main compounds of cell wall or reservoir. Among reservoir compounds, it included cotyledonary xyloglucans and endospermic galactomannans. The xyloglucans are made of a main chain of β-D-(1→4)-glucan with α-(1→6) ramifications of D-xylopyranoside or β-D-galactopyranoside-(1→2)-D-xylopyranoside residues. Endospermic galactomannans are polimeric chains of β-D-mannopyranosil (1→4) and replaceabled in O-6 for units of α-D-galactopyranosil. The aim of this work is investigate the interaction of xyloglucans and galactomannans with galactose bounding lectins and show the possibility of the usage of these polysaccharides as cheap and useful chromatographic matrices for isolation and determination of anomeric specificity of galactose bounding lectins. The interactions of lectins from seeds of Artocarpus integrifolia (frutalin), Artocarpus incisa (jacalin), Ricinus communis (ricin) e Arachis hypogaea (PNA) were performed with coluns of xyloglucans of seeds from Copaifera langsdorffii, Mucuna sloanei and Hymenaea courbaril (MC, MMu, MJ, respectively) and galactomannans from Mimosa scabrella, Stryphnodendron barbatiman, Adenanthera pavonina and Dimorphandra mollis (MM, MS, MA; MD, respectively). The galactomannans showed the best colun interaction capacity for the jacalin (MA â 0,92 mg ; MM â 1,48 mg ; MD â0,88 mg ; MS â 0,83 mg) and frutalin (MA â 0,99 mg ; MM â 1,09 mg ; MD - 0,94 mg ; MS - 0,85 mg) lectins. Remarkably the M. scabrella galactomannan showed the best colun interaction among all lectins analysed. On the other hand, ricin was better hold in coluns made of xyloglucan (MMu â 2,17 mg ;MJ â 1,30 mg; MC â 2,83 mg). For PNA lectin, differences were detected in colun interaction capacity. The best colun interaction was with the M. sloanei matrix (0,12 mg) for PNA lectin. All coluns were fill with sample extract of flour from seeds and hemagglutination assays was performed with PI and PII. In these assays, hemagglutination activity was detected in both PI and PII from the coluns. For ricin, toxic activity was made and it was detected for all obtained chromatographic samples. With SDS-PAGE it was possible confirmed the purification of the studied lectins. The bands in polyacrilamid gel were the same for the lectins purified. In conclusion, it can be suggested the usage of xyloglucans and galactomannans for isolation, purification and determination of anomeric specificity of galactose-bounding lectins.
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Lobo, Marina Duarte Pinto. "AnÃlise proteÃmica de plasma de pacientes com cÃncer de mama utilizando lectinas vegetais e label-free LC-MSE". Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16410.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO cÃncer de mama representa o tipo de cÃncer mais comum entre as mulheres no mundo e no Brasil, depois do cÃncer de pele nÃo melanoma. Caracterizando-se como uma doenÃa clÃnica e biologicamente heterogÃnea, a detecÃÃo precoce do cÃncer de mama, uma caracterizaÃÃo fidedigna da doenÃa e um diagnÃstico preciso sÃo de fundamental importÃncia para reduÃÃo da mortalidade. Assim, o objetivo do presente trabalho foi realizar anÃlises qualitativas e quantitativas de proteÃnas plasmÃticas de mulheres saudÃveis e mulheres com cÃncer de mama tipo ductal, em diferentes estÃgios. Para isso, inicialmente, as amostras de plasma foram depletadas de albumina e IgG e depois reunidas em pools representativos para cada grupo em estudo. Os pools foram entÃo fracionados por meio de cromatografias de afinidade em matrizes de Sepharose 4B imobilizadas com as lectinas vegetais α-galactose-ligante de Artocarpus incisa - Frutalina e glucose/manose-ligante de Dioclea altÃssima â DAL. Posteriormente, tantos os pools como as fraÃÃes cromatogrÃficas obtidas foram digeridas e submetidas à anÃlise independente de dados (MSE) e quantificadas (label-free) por espectrometria de massas. A utilizaÃÃo das cromatografias de afinidade com lectinas vegetais a priori da anÃlise por espectrometria de massas foi fundamental para reduzir a complexidade das amostras e estender o intervalo dinÃmico de proteÃnas, e frutalina apresentou os melhores resultados de fracionamento. Um somatÃrio de todas as anÃlises realizadas revelou a identificaÃÃo de cerca de 445.000 peptÃdeos e mais de 30.000 proteÃnas, com redundÃncia entre isoformas do mesmo grupo e entre grupos. Ademais, alÃm de fracionar, as cromatografias de afinidade com lectinas vegetais foram eficientes em isolar glicoformas especÃficas que refletem um padrÃo de glicosilaÃÃo alterado associado à doenÃa. Diversas proteÃnas diferencialmente expressas, algumas delas com mudanÃas na glicosilaÃÃo, foram identificadas, tais como apolipoproteÃna A2, apolipoproteÃna C3, fatores do sistema complemento (C3, C4b e C4A), clusterina, α-1-2-Ãcido glicoproteÃna, haptoglobina, hemopexina, paraoxonase arilesterase sÃrica, proteÃna plasmÃtica de ligaÃÃo ao retinol, plasminogÃnio e vitronectina. Dentre as proteÃnas identificadas, algumas estÃo relacionadas com a decomposiÃÃo da matriz extracelular, metabolismo lipÃdico, estresse oxidativo e outras caracterizam-se como proteÃnas de fase aguda. Finalmente, os dados de expressÃo diferencial e possÃveis alteraÃÃes de glicosilaÃÃo das proteÃnas contribuem para o desenvolvimento de um perfil protÃico, alvo para posterior validaÃÃo, que apresenta uma associaÃÃo com o desenvolvimento e a caracterizaÃÃo do cÃncer de mama em seus diferentes estÃgios.
The breast cancer presents one of the most commonly diagnosed types of cancer among women worldwide and in Brazil, after nonmelanoma skin cancer. Itâs a clinically and biologically heterogeneous disease. Therefore, early detection of breast cancer, a reliable characterization of the disease and an accurate diagnosis are crucial to reducing mortality. The aim of this work was perform a qualitative and quantitative analyzes of plasma proteins from healthy women and from women with ductal breast cancer in different stages. For this, initially, plasma samples were depleted of IgG and albumin and then pooled into samples representative for each study group. The pools were then fractionated by immobilized plant lectins (frutalin and DAL)-affinity chromatography. Subsequently, the pools and chromatographic fractions were digested and submited to and data-independent label-free mass spectrometric analysis. The use of affinity chromatography with plant lectins prior to analysis by mass spectrometry was essential to reduce sample complexity and extend the dynamic range of proteins, and frutalin showed the best results from fractionation. A sum of all analyzes performed revealed the identification of about 445,000 peptides and more than 30,000 proteins, with redundancy between isoforms of the same group and between groups. Furthermore, in addition to fractionation, the chromatography of affinity with plant lectins were effective in isolating specific glycoforms that reflect an altered glycosylation pattern associated with the disease. Several differentially expressed proteins, some of which changes in glycosylation were identified, such as apolipoprotein A2, apolipoprotein C3, complement factors (C3, C4b and C4A), clusterin, 1-2-α-acid glycoprotein, haptoglobin, hemopexin, serum paraoxonase arylesterase, plasma retinol binding protein, plasminogen and vitronectin. Among the proteins identified, some are related to the breakdown of the extracellular matrix, lipid metabolism, oxidative stress and other characterized as acute phase proteins. Finally, the data of differential expression and possible changes in the glycosylation patterns of proteins contributes to the development of a protein profile, subject to later validation, presenting an association with the development and characterization of breast cancer in its different stages.
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Sousa, Bruno Lopes de. "Caracterização estrutural das formas silvestre e recombinante de uma lectina de sementes de Vatairea macrocarpa Benth e análise das suas bases moleculares de ligação ao antígeno Tn". reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/18875.
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SOUSA, Bruno Lopes de.Caracterização estrutural das formas silvestre e recombinante de uma lectina de sementes de Vatairea macrocarpa Benth e análise das suas bases moleculares de ligação ao antígeno Tn. 2014. 119 f. Tese (Doutorado em Bioquímica)-Universidade Federal do Ceará, Fortaleza-CE, 2014.Submitted by Eric Santiago (erichhcl@gmail.com) on 2016-07-20T12:14:08Z No. of bitstreams: 1 2014_tese_blsousa.pdf: 4344064 bytes, checksum: 784bc6294f0c6ff7014ef6c5ecece099 (MD5)
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Lectins are a very diverse class of proteins able to bind specific sugar structures reversibly and with high specificity, but without enzymatically modifying them, triggering several important cellular processes. Among the different lectin families, legume lectins are the most thoroughly studied and have been widely reported to exhibit a number of links to many pathological processes, including carcinogenesis. The remarkable anti-tumor properties of some legume lectins, resulting from their ability to induce programmed cell death and/or autophagocytosis in cancer cells have attracted much attention for biomedical applications. Moreover, a few galactose/N-acetylgalactosamine (Gal/GalNAc)-binding lectins from this group have proven to be useful markers for cancer histochemistry, and the structural characterization of these lectins bound to specific cancer epitopes has been carried out successfully. The seed lectin isolated from the legume tree Vatairea macrocarpa (VML) is a well characterized Gal/GalNAc-binding protein able to specifically recognize naturally occurring O-mucins presenting the carcinoma epitope Tn antigen (GalNAc-α-O-Ser). The crystal structures of VML in complex with Tn antigen and GalNAc have been determined at the resolution of 1.4 and 1.7 Å, respectively. Unfortunately, most of lectins obtained from natural sources consist in a mixture of forms, which is an undesired feature for biomedical applications. Thus, the recombinant form of VML (rVML) was expressed in Escherichia coli, being obtained soluble and wih high yielding. The crystal structure for rVML, as well as for the complex with Tn antigen, GalNAc and α-Lactose have been determined at resolutions of 1.7, 2.7, 2 and 1.8 Å, respectively, presenting the same overall structure and binding patterns as the wild lectin. Molecular docking analysis of this new structure and other Tn-binding legume lectins to O-mucin fragments differently decorated with this antigen provides a comparative binding profile among these proteins, stressing that subtle alterations that may not influence monosaccharide binding can, nonetheless, directly impact the ability of these lectins to recognize naturally occurring antigens. In addition to the specific biological effects of VML, the structural and binding similarities between it and other lectins commonly used as histological markers (e.g., VVLB4 and SBA) strongly suggest that VML can be used as a new tool for cancer research. This is the first report of crystal structures of a Gal/GalNAc-binding legume lectin from the Dalbergieae tribe.
As lectinas consitem em uma classe diversificada de proteínas, capazes de reconhecer estruturas glicídicas de forma reversível e com alta especificidade, no entanto sem alterar suas estruturas químicas, participando de vários processos celulares importantes. Dentre as diferentes famílias de lectinas, as isoladas a partir de leguminosas são as mais extensivamente estudadas, havendo sido relatada a influências dessas moléculas sobre diversos processos patológicos, incluindo a carcinogênese. Notáveis propriedades antitumorais têm sido detectadas para algumas lectinas de leguminosas, resultantes da sua habilidade em induzir a morte celular ou a autofagia em células cancerígenas, o que atraído atenção para suas possiveis aplicações biomédicas. Além disso, algumas lectinas desse grupo especificas para galactose/N-acetil-D-galactosamina (Gal/GalNAc) têm se mostrado úteis como marcadores histoquímicos na pesquisa do câncer e a caracterização estrutural dessas lectinas em complexo com diferentes epítopos cancerígenos vem sendo realizada com sucesso. A lectina isolada a partir das sementes da leguminosa Vatairea macrocarpa (VML) é uma lectina bem caracterizada específica para Gal/GalNAc capaz de reconhecer especificamente o antígeno Tn (GalNAc-α-O-Ser), naturalmente encontrado em O-mucinas presentes em diferentes tipos de câncer. As estruturas cristalográficas para a VML em complexo com o antígeno Tn e GalNAc foram determinadas com resoluções de 1.4 e 1.7 Å, respectivamente. A maioria das lectinas obtidas a partir de fontes naturais consiste em misturas de diferentes isoformas, uma característica indesejada para aplicações biomédicas. Com base nisso, uma construção recombinante para VML (rVML) foi expressa em Escherichia coli, sendo obtida de forma solúvel em com alto rendimento. A estrutura cristalina para a rVML, bem como para seus complexos com o antígeno Tn, GalNAc e α-Lactose foram determinadas com resoluções de 1.7, 2.7, 2 e 1.8 Å, respectivamente, apresentando a mesma estrutura geral e padrões de interação que a lectina silvestre. Com o intuito de gerar um perfil comparativo entre a VML e outras lectinas de leguminosas capazes de reconhecer o antígeno Tn, foram realizadas análises de docking molecular utilizando fragmentos de O-mucinas diferentemente decorados com o antígeno Tn. Esse perfil ressalta como alterações sutis no elenco ou disposição dos aminoácidos constituintes do sítio de ligação a carboidrato, que talvez não influenciem a capacidade de ligação a monossacarídeo, podem impactar diretamente a habilidade dessas lectinas em reconhecer antígenos em condições naturais. Adicionalmente aos já caracterizados efeitos biológicos relatados para VML, a similaridade entre sua estrutura e perfis de interações quando comparadas a outras lectinas comumente utilizadas como marcadores histoquímicos (e.g., VVLB4 e SBA), sugerem fortemente a possível utilização da VML como uma nova ferramenta na pesquisa do câncer. Esse trabalho consiste no primeiro relato de estruturas cristalográficas para uma lectina de leguminosa específica para Gal/GalNAc da tribo Dalbergieae.
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Landim, Patrícia Gadelha de Castro. "Xiloglucanas e galactomananas de leguminosas: interação com lectinas D-galactose-ligantes". reponame:Repositório Institucional da UFC, 2007. http://www.repositorio.ufc.br/handle/riufc/18846.
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LANDIM, Patrícia Gadelha de Castro. Xiloglucanas e galactomananas de leguminosas: interação com lectinas D-galactose-ligantes. 2007. 100 f. Dissertação (Mestrado em Bioquímica) - Universidade Federal do Ceará, Fortaleza-CE, 2007.Submitted by Eric Santiago (erichhcl@gmail.com) on 2016-06-27T12:54:01Z No. of bitstreams: 1 2007_dis_pgclandim.pdf: 1768165 bytes, checksum: f8cb9e6a16de4f08d984b33f047c8bd5 (MD5)
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Polysaccharides are found in large quantity in seeds and they represent the main compounds of cell wall or reservoir. Among reservoir compounds, it included cotyledonary xyloglucans and endospermic galactomannans. The xyloglucans are made of a main chain of β-D-(1→4)-glucan with α-(1→6) ramifications of D-xylopyranoside or β-D-galactopyranoside-(1→2)-D-xylopyranoside residues. Endospermic galactomannans are polimeric chains of β-D-mannopyranosil (1→4) and replaceabled in O-6 for units of α-D-galactopyranosil. The aim of this work is investigate the interaction of xyloglucans and galactomannans with galactose bounding lectins and show the possibility of the usage of these polysaccharides as cheap and useful chromatographic matrices for isolation and determination of anomeric specificity of galactose bounding lectins. The interactions of lectins from seeds of Artocarpus integrifolia (frutalin), Artocarpus incisa (jacalin), Ricinus communis (ricin) e Arachis hypogaea (PNA) were performed with coluns of xyloglucans of seeds from Copaifera langsdorffii, Mucuna sloanei and Hymenaea courbaril (MC, MMu, MJ, respectively) and galactomannans from Mimosa scabrella, Stryphnodendron barbatiman, Adenanthera pavonina and Dimorphandra mollis (MM, MS, MA; MD, respectively). The galactomannans showed the best colun interaction capacity for the jacalin (MA – 0,92 mg ; MM – 1,48 mg ; MD –0,88 mg ; MS – 0,83 mg) and frutalin (MA – 0,99 mg ; MM – 1,09 mg ; MD - 0,94 mg ; MS - 0,85 mg) lectins. Remarkably the M. scabrella galactomannan showed the best colun interaction among all lectins analysed. On the other hand, ricin was better hold in coluns made of xyloglucan (MMu – 2,17 mg ;MJ – 1,30 mg; MC – 2,83 mg). For PNA lectin, differences were detected in colun interaction capacity. The best colun interaction was with the M. sloanei matrix (0,12 mg) for PNA lectin. All coluns were fill with sample extract of flour from seeds and hemagglutination assays was performed with PI and PII. In these assays, hemagglutination activity was detected in both PI and PII from the coluns. For ricin, toxic activity was made and it was detected for all obtained chromatographic samples. With SDS-PAGE it was possible confirmed the purification of the studied lectins. The bands in polyacrilamid gel were the same for the lectins purified. In conclusion, it can be suggested the usage of xyloglucans and galactomannans for isolation, purification and determination of anomeric specificity of galactose-bounding lectins.
Polissacarídeos ocorrem em grandes quantidades nas sementes como componentes da parede celular ou como reserva. Dentre estes últimos, incluem-se as xiloglucanas cotiledonárias e as galactomananas endospérmicas. As xiloglucanas apresentam uma cadeia principal de β-D-(1→4)-glucana ramificada com ligações α-(1→6) por resíduos D-xilopiranosídeos ou β-D-galactopiranosídeo-(1→2)-D-xilopiranosídeos, enquanto as galactomananas endospérmicas consistem em cadeias poliméricas de resíduos β-D-manopiranosil (1→4) ligados, substituídos em O-6 por unidades de α-D-galactopiranosil. O objetivo deste trabalho foi analisar a interação de xiloglucanas e galactomananas com lectinas galactose-ligantes e, assim, sugerir o uso de tais polissacarídeos como alternativa barata e eficaz na preparação de matrizes cromatográficas para o isolamento e determinação da especificidade anomérica de novas lectinas. Dessa forma, as interações das lectinas das sementes de Artocarpus integrifolia (frutalina), Artocarpus incisa (jacalina), Ricinus communis (ricina) e Arachis hypogaea (PNA) com matrizes de xiloglucanas de sementes de Copaifera langsdorffii, Mucuna sloanei e Hymenaea courbaril (MC, MMu, MJ, respectivamente) e de galactomananas de Mimosa scabrella, Stryphnodendron barbatiman, Adenanthera pavonina e Dimorphandra mollis (MM, MS, MA; MD, respectivamente) foram analisadas. As galactomananas apresentaram melhor capacidade de retenção da jacalina (MA – 0,92 mg ; MM – 1,48 mg ; MD –0,88 mg ; MS – 0,83 mg) e da frutalina (MA – 0,99 mg ; MM – 1,09 mg ; MD – 0,94 mg ; MS – 0,85 mg), lectinas que possuem especificidade por α-D-galactose. Vale destacar que a galactomanana de M. scabrella apresentou melhor capacidade de retenção da lectinas testadas. Por outro lado a ricina, capaz de ligar-se aos dois anômeros, mas que se liga preferencialmente ao anômero β, teve maior massa retida nas colunas de xiloglucana (MMu – 2,17 mg ;MJ – 1,30 mg; MC – 2,83 mg). Houve diferença nos perfis de retenção da PNA, que também se liga aos anômeros α e β da galactose, sendo que a melhor retenção foi na coluna contendo matriz de M. sloanei (0,12 mg). As colunas foram todas saturadas com extrato bruto a partir das farinhas das sementes, para que se utilizasse a capacidade máxima de retenção de cada matriz. Atividade hemaglutinante foi detectada em ambos os picos PI e PII. Para a ricina, atividade tóxica foi realizada e detectada para todos os PII obtidos. Por meio de SDS-PAGE, a pureza de cada uma das lectinas foi confirmada. Diante dos resultados expostos, pode-se sugerir o uso de xiloglucanas e galactomananas para o isolamento, purificação e determinação da especificidade anomérica de lectinas galactose-ligantes.
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Kohatsu, Luciana. "Novel roles for human lectins in innate defense against pathogens". Diss., Restricted to subscribing institutions, 2006. http://proquest.umi.com/pqdweb?did=1155572661&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Johansson, Emma M. V. "Combinatorial discovery of glycopeptide dendrimers targeting lectins /". [S.l.] : [s.n.], 2009. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Vieira, Breitwieser Otilia. "Leguminous lectins bind non specifically to DNA". [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=972705589.
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Hutchinson, Oliver Clyde. "The isolation and characterization of fungal lectins". Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322949.
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Al-Abbasi, Fahad Ahmed. "Application of lectins to specific analytical problems". Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438401.
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Carter, Tom Scott. "Synthetic lectins with pyrene at the core". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702443.
Texto completoResumen
Carbohydrates are displayed on the outer layer of cells by glycoproteins and glycolipids, forming the glycocalyx. These carbohydrates hold a huge amount of information, acting as a cell 'barcode', facilitating communication and acting as targets for pathogens. The proteins which recognise carbohydrates in nature are called lectins. Synthetic mimics of these proteins, binding through noncovalent interactions in water, are termed 'synthetic lectins'. The design and synthesis of these synthetic lectins could allow reading of parts of the cell barcode and give a greater understanding of the operation of natural lectins. Furthermore, robust selective synthetic lectins could act as sensors for important sugars such as N-acetylglucosamine (important in protein regulation) or blood glucose levels (for surgery or diabetics). However the design of synthetic lectins that are able to overcome the hydromimetic nature of carbohydrates and show selectivity between carbohydrates is very difficult. Within this body of work a variety of synthetic lectin architectures are presented, with their design, synthesis and binding properties reported. Two designs within are of particular note. Firstly, a highly cationic pyrene based platform shaped receptor (PyPlat-Guan) was prepared to target α-sialosides (components of important antigens such as Sialyl Lewis X). This resulted in strong selective binding of methyla α-sialoside and both the first non-macrocyclic synthetic lectin and the first synthetic lectin with divalency by design. Secondly, a pyrene based four-pillared cage receptor was prepared (Py4P) to target O-linked N-acetylglucosamine (O-GlcNAc). This resulted in a pair of receptor isomers, which demonstrate the highest binding affinities ever obtained by a synthetic lectin for a monosaccharide. It was then also possible to test the interaction of these synthetic lectins with a glycopeptide, which was bound with unprecedented affinity.
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Barroso, Neto Ito Liberato. "Resolução da estrutura tridimensional de uma lectina de sementes de Canavalia grandiflora Benth. com efeitos sobre mecanismos inflamatórios". reponame:Repositório Institucional da UFC, 2010. http://www.repositorio.ufc.br/handle/riufc/18171.
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BARROSO NETO, Ito Liberato. Resolução da estrutura tridimensional de uma lectina de sementes de Canavalia grandiflora Benth. com efeitos sobre mecanismos inflamatórios. 2010. 103 f. Dissertação (Mestrado em Bioquímica) - Universidade Federal do Ceará, Fortaleza-CE, 2010.Submitted by Eric Santiago (erichhcl@gmail.com) on 2016-05-25T12:16:49Z No. of bitstreams: 1 2010_dis_ilbarrosoneto.pdf: 2893401 bytes, checksum: 790650a62ad9b6de91f47b92f3115778 (MD5)
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Plant Lectins can be defined as non-immune origin proteins having at least one non-catalytic domain that binds reversibly in a specific fashion to a mono-or oligosaccharide. The legume lectin family group represents the best studied of these proteins, in particular highlighted the subtribe Diocleinae, which has the best characterized representative, ConA. Lectins Diocleinae show a high degree of structural similarity, but the same does not regarding biological activities and specificity to different carbohydrates, which makes it important to research in structural and biological levels of its various members, among them the Canavalia grandiflora Benth. The lectin from Canavalia grandiflora (Congr) was purified according to Ceccato (2001) and was crystallized by vapor diffusion method at 293 K. Crystals were obtained in a state containing 0.5 M of cadmium sulfate hydrate, 0.1 M HEPES pH 7.5 and 1.0 M sodium acetate trihydrate. The crystals have the orthorhombic space group I222, the unit cell has the dimensions a = 67.70 Å, b = 55.90 Å and c = 107.46 Å and angles? =? =? = 90 °, giving a monomer in the asymmetric unit and a content of 42.53% solvent in the crystal. The structure was solved to 2.19 Å and phase problem was solved by the method of molecular replacement using the coordinates of Canavalia gladiata as a template (PDB: 2D7F). The refinement showed satisfactory "rfactor" and "Rfree" with 22.6 and 27.4 respectively and only one amino acid residue in a region of the Ramachandran disallowed. Despite the high structural similarity, small changes in the direction of key amino acids may be responsible for the diversity in the biological applications as a result of the residues of the carbohydrate binding site which are retained despite changes in spatial orientation. The primary sequence of the lectin from C. grandiflora has great similarity with lectins of the same genus, but it has the largest number of mutations representative of the genus Dioclea, characterizing it as the subgenus Canavalia nearest Dioclea and canavalias is among the most primitive. The Congregation edamatogênica showed activity in a model of paw edema (sc) and relaxing effect on smooth muscle of rat aorta endothelial, but the effects appear to be weak compared to other lectins Diocleinae.
Lectinas de plantas podem ser definidas como proteínas de origem não imune que possuem pelo menos um domínio não catalítico que se liga reversivelmente de maneira específica a um mono- ou oligossacarídeo. A família das lectinas de leguminosas representa o grupo destas proteínas mais bem estudadas, em especial destaque a subtribo Diocleinae, que possui o representante mais bem caracterizado, a ConA. As lectinas de Diocleinae apresentam um alto grau de similaridade estrutural, porém o mesmo não ocorre quanto às atividades biológicas e especificidade a carboidratos variados, o que torna importante a investigação em níveis estruturais e biológicos dos seus diversos membros, dentre eles a Canavalia grandiflora Benth. A lectina de sementes de Canavalia grandiflora (ConGr) foi purificada de acordo com Ceccato (2001) e foi cristalizada pelo método de difusão de vapor a 293 K. Cristais foram obtidos em uma condição contendo 0,5 M de sulfato de cádmio hidratado, 0,1 M de HEPES pH 7.5 e 1,0 M de acetato de sódio triidratado. Os cristais apresentam o grupo espacial ortorrômbico I222, a cela unitária tem como dimensões a=67,70 Å, b=55,90Å e c=107,46 Å e ângulos ?=?=?=90º, sendo observado um monômero na unidade assimétrica e um conteúdo de 42,53% de solvente no cristal. A estrutura foi resolvida a 2,19Å e o problema de fase foi solucionado pelo método de substituição molecular utilizando as coordenadas da Canavalia gladiata como modelo (PDB: 2D7F). O refinamento satisfatório apresentou “Rfactor” e “Rfree” com 22,6 e 27,4 respectivamente e apenas um resíduo de aminoácido em região não permitida do Ramachandran. Apesar da alta similaridade estrutural, pequenas mudanças na orientação de aminoácidos chaves, podem ser responsáveis pela diversidade nos resultado de aplicações biológicas como os resíduos do sítio de ligação a carboidrato, que apesar de conservados possuem modificações na orientação espacial. A seqüência primária da lectina de C. grandiflora apresenta grande similaridade com lectinas do mesmo gênero, porém ela concentra o maior número de mutações representativas do gênero Dioclea, caracterizando-o como o subgênero de Canavalia mais próximo de Dioclea, e dentre as canavalias é a mais primitiva. A ConGr apresentou atividade edamatogênica em modelo de edema de pata (s.c.) e efeito relaxante em músculo liso de aortas de ratos endotelizadas, porém os efeitos mostram-se fracos frente a outras lectinas de Diocleinae.
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Oliveira, Mara Rubea Tinoco Rodrigues de. "Avaliação in vitro do efeito de lectinas de sementes de Talisia esculenta e Labramia bojeri sobre o biofilme oral". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288965.
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Orientadores: Francisco Carlos Groppo, Maria das Graças Machado FreireDissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: A medicina natural e complementar, especialmente a fitoterapia, suprem as necessidades em saúde de grande parte da população, particularmente nos países em desenvolvimento. Dentre os fitoterápicos, as lectinas podem ter valia como agentes antiplaca, uma vez que podem estar intimamente relacionadas com a aderência de microrganismos. O objetivo deste estudo foi testar in vitro a capacidade de inibição das lectinas isoladas (TEL - derivada da semente de Talisia esculenta e LABRAMIN - purificada da planta Labramia bojeri), na adesão e crescimento de microrganismos orais (Streptococcus sanguinis, S. mitis, S. oralis, S. mutans, S. sobrinus). A atividade antimicrobiana das duas lectinas foi determinada pelo teste convencional da macrodiluição de caldo, sendo testada as concentrações de 400, 200, 100, 50, 25 µg/mL contra 105 CFU/mL dos microrganismos em estudo. Os tubos foram incubados (10% CO2, 37oC, 18h) e submetidos à leitura de densidade óptica (OD a 600nm). A MBC foi determinada pela adição das amostras de cada tubo em placas de petri contendo agar BHI (10% CO2, 37oC, 18h). Para avaliação de aderência foi feito um ensaio semiquantitativo de aderência em placas de microtitulação de poliestireno, onde foi adicionado 100 µL de saliva clarificada e incubada por 2h a 37°. Após lavagem com PBS, foram adicionadas às placas em triplicata 100 µL de lectinas (6.25, 12.5, 25, 50 e 100 µg/mL) e incubados durante 1h. A seguir foi adicionada 100 µL de suspensão bacteriana (106 UFC/mL) e incubado a 37ºC em uma atmosfera de 10% de CO2. A aderência foi revelada e quantificada por tintura com cristal violeta. A absorção do cristal violeta foi determinada por um leitor de placa (575nm). Nem a TEL nem a LABRAMIN foram capazes de inibir ou matar os microorganismos estudados. No teste de inibição de aderência, a LABRAMIN reduziu significativamente a aderência de S. mutans e S. sobrinus, na concentração de 100µg (p< 0,05). A TEL não inibiu a aderência dos estreptococos e ainda favoreceu a aderência do S. mitis. Concluiu-se que embora nenhuma das lectinas estudadas tenham atividade antimicrobiana, a LABRAMIN foi capaz de inibir a aderência de estreptococos cariogênicos
Abstract: Natural and complementary medicine, with special regard to phytotherapy, provide care for health needs of a great part of the world¿s population, particularly in developing countries. Among phytotherapic compounds, lectins could be of value as anti-plaque agents, once they can be closely related to microorganisms¿ adherence. Our study intended to test, in vitro, the capacity of two isolated lectins ¿ TEL (derived from Talisia esculenta seeds) and LABOL (purified from the plant Labramia bojeri ¿ for inhibiting the adherence and growth of oral microorganisms (Streptococcus sanguinis, S. mitis, S. oralis, S. mutans, S. sobrinus). Both lectins¿ antimicrobial activities were determined by a conventional macrodilution broth test. Study¿s microorganisms concentrations were tested for 400, 200, 100, 50, 25 µg/mL against 105 CFU/mL. Tubes were incubated (10% CO2, 37oC, 18h) and submitted to optical density reading (OD at 600nm). MBC was determined by the addition of samples from each tube to petri dishes containing agar BHI (10% CO2, 37oC, 18h). A semiquantitative assay was performed for adherence assessment in polystyren microtiter plates. A hundred microliter (100µL) of clarified saliva were added and incubated for 2h at 37°. Following PBS wash, 100 µL lectins (6.25, 12.5, 25, 50 e 100 mg/mL) were added to the triple plates and incubated for 1h. Then, 100 µL of bacterial suspension (106 UFC/mL) were added and incubated at 37ºC in a 10% CO2 atmosphere. Adherence was revealed and quantified by crystal violet staining. A plate reader (575nm) determined crystal violet absorbance. Nor TEL nor LABOL were able to inhibit or kill the studied microorganisms. Regarding adherence inhibition, 100µg concentration of LABOL showed statistically significant (p < 0.05) on S.mutans and S. sobrinus. TEL did not inhibt streptococci adherence; yet, it favored S. mitis adherence. It was concluded that, although none of the studied lectins had presented antimicrobial activity, LABOL was capable of inhibiting cariogenic streptococci adherence. Further studies will be necessary to assess such lectins¿ potential over other microorganisms and over oral biofilm
Mestrado
Mestre em Odontologia em Saúde Coletiva
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Silveira, Willian Abraham da. "Avaliação da interação entre galectina-1 e zinco e suas potenciais implicações estruturais e funcionais". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/60/60135/tde-05072011-122646/.
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Introdução: A Galectina-1 (Gal-1) é uma proteína multifuncional capaz de reconhecer, de modo específico, glicanas compostas por resíduos de -galactosídeos, por meio de domínios de reconhecimento de carboidrato (CRD). A Gal-1 é um homodímero de 14.900 daltons, pI = 5.6, apresenta uma topologia molecular do tipo jelly-roll composto por duas folhas- anti-paralelas. Além disso, esta proteína não apresenta peptídeo sinal e possui 6 cisteínas, 7 ácidos glutâmicos, 9 ácidos aspárticos e 4 histinas por monômero. A Gal-1 liga-se a diferentes moléculas biológicas contidas nas superfícies celulares, núcleo e componentes da matriz extracelular. O zinco é um importante metal em sistemas biológicos. Aproximadamente 10% do proteoma humano é potencialmente capaz de complexar zinco. Este íon exibe propriedades adequadas tanto para funções catalíticas, quanto estruturais em proteínas. Os sítios de ligação a zinco, nas proteínas, podem ser divididos em catalíticos, estruturais, co-catalíticos e sítios na interface protéica. Geralmente, os resíduos de cisteína, histidina, ácido glutâmico e ácido aspártico são alvos preferênciais de interação com Zn. Há na literatura dados que mostram a interação da Gal-1 humana com íons orgânicos, porém não há relatos sobre a interação Gal-1/Zn . Objetivos: O presente trabalho teve como objetivo avaliar a existência e as implicações da interação entre o íon Zn2+ e a proteína Gal-1. Materiais e Métodos: Foi efetuada a produção, purificação e padronização do uso das formas dimérica e monomérica da Gal-1 recombinante humana. A interação Gal-1/Zn foi avaliada através de ensaios biofísicos e biológicos. A análise in vitro e in silico dos paramêtros biofísicos, foi feita através de espectrofluorimetria, de dicroísmo circular, de ensaio de precipitação, do método GRID e por dinâmica molecular. A análise in vitro dos parâmetros biológicos, foi realizada por meio de ensaio de hemaglutinação e interação com laminina por ELISA. Resultados e Discussão: A adição de ZnCl2 numa solução de Gal-1 causa aumento da emissão por fluorescência do triptofano e uma alteração para o vermelho, altera o espectro de dicroísmo circular e causa precipitação protéica da Gal-1. Estes eventos ocorreram de forma seletiva e dependente da concentração desse íon. As análises in silico indicam que o provável sítio de complexação Zn/Gal-1 é distinto do CRD e é formado pelos aminoácidos Glu-15, Asp-92 e Asp-134, assumindo a conformação trigonal bipiramidal e tendo número de coordenação igual a 5. Conclusão: As análises biofísicas in vitro e in silico, nos indicam que a Galectina-1 tem a capacidade de se complexar com o íon Zn2+.Introduction: Galectin-1 (Gal-1) is a multifunctional protein that specifically recognizes glycans with -galactosides through carbohydrate recognition domains (CRD). Gal-1 is a homodimeric protein of 14.900daltons, pI=5.6, shows a jelly-roll molecular topology composed of two anti-parallels - sheet, has no signal peptide and contains 6 cysteines, 7 glutamic acids, 9 aspartic acids and 4 histidines per monomer. This lectin binds to different biological molecules contained in the cell surface, nucleus and extracellular matrix components. Zinc is an important metal in biological systems because can participate in the maintenance of protein structure and biological activity. Usually, cysteine , histidine, glutamic acid and aspartic acid residues are preferential targets for interaction with Zn. Approximately 10% of the human proteome is potentially capable to forming complexes with Zn. The Zn2+ ion exhibits properties suitable for both catalytic and structural protein functions. Proteins zinc binding sites can be divided into catalytic, structural, co-catalytic and protein interface sites.There are reports in the literature that shows the interaction between galectin-1 and organic ions. However, were not found reports about Zn-Gal-1 complexes. Objective: The aim of this study was to evaluate the existence and implications of the interaction between galectin-1 and Zn2+ ion. Materials and Methods: Human recombinant Gal-1 (monomer and dimmer) was obtained and purified. Also, the conditions for the use of Gal-1 were standardized. The interaction Zn/Gal-1 was assessed by biophysical an biological procedures. The analysis in vitro and in silico was made by spectrofluorimetry, circular dichroism, precipitation test, method of GRID, and molecular dynamics. The in vitro analysis of biological parameters were performed by hemmaglutination and laminin binding (ELISA) tests. Results and Discussion: The addition of ZnCl2 in Gal-1 solution causes increased fluorescence emission of tryptophan-70 and a red shift, alters the circular dichroism spectrum and causes precipitation of Gal-1 protein. These events occurred in a selective manner dependent of Zinc concentration. The in silico analysis indicates that the probable site of Zn/Gal-1 complexation is distinct from the CRD and is formed by the amino acids Glu-15, Asp-92 and Asp-134, assuming trigonal bipyramidal conformation and with coordination number equal to 5 . Conclusion: The biophysical in vitro and in silico findings suggests that Galectin-1 has the ability to complex with the Zn2+ ion.
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Carding, S. R. "Immunochemical studies of mammalian beta-galactoside ?-binding lectins". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.352601.
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Barwell, Nicholas P. "Synthetic lectins : biomimetic receptors for carbohydrates in water". Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495920.
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Raemaekers, Romaan J. M. "Expression of functional plant lectins in heterologous systems". Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4621/.
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The mannose-binding lectin from snowdrop (Galanthus nivalis agglutinin; GNA) was produced in Escherichia coli and purified as a functional protein after denturation/renaturation. Incorporation of the four extra C-terminal residues recently revealed from X-ray crystallographic data demonstrated that these residues increase binding to the glycoprotein carboxypeptidase Y. However, no differences in activities were observed in haemagglutination assays when compared to native GNA and toxicity towards rice brown planthopper (Nilaparvata lugens', BPH) in artificial diet bioassays was unaltered. Site-directed mutagenesis of the carbohydrate-binding site of GNA provided evidence of a direct correlation between the binding potential of GNA to BPH gut glycoprotein 'receptors' and the toxicity levels of GNA towards BPH nymphs. Functional recombinant plant lectins GNA and PHA (Phaseolus vulgaris agglutinin) were expressed in Pichia pastoris using native signal peptides or the Saccharomyces a-factor prepro-sequence to direct secretion. The a-factor prepro-sequence was inefficiently processed unless Glu-Ala repeats were added at the C-terminal end. In the latter case, removal of the Glu-Ala repeats was itself inefficient leading to recombinant lectins with heterogenous N-termini. In contrast, PHA expressed with the native signal peptide was secreted, correctly processed and fully functional. No expression of GNA from a construct containing the native GNA signal peptide was observed. The PHA-E signal peptide directed correct processing and secretion of both GNA and green fluorescent protein (GFP) when used in expression constructs in Pichia. A fusion protein containing both GNA and GFP (GNA-GFP) was expressed in Pichia pastoris. Simultaneous dual activities (i.e. carbohydrate binding and fluorescence) of recombinant GNA-GFP were demonstrated. Partial cleavage in the linker region resulted in co-purification of GNA which increased the binding activity of the fusion protein. Selective binding of GNA-GFP to haemocytes in the haemolymph of Lacanobia oleracea was observed, both in vitro and when the protein was fed to insects in diet.
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Woodhouse, Stephen David. "Binding and toxicity of plant lectins to insects". Thesis, Durham University, 2002. http://etheses.dur.ac.uk/4103/.
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The toxicity of plant lectins to insects after oral ingestion was investigated by incorporating the proteins into insect diets. Bioassays carried out using an artificial diet system demonstrated that kidney bean (Phaseolus vulgaris) lectin (PHA) caused a significant decrease in survival of larvae of the tomato moth, Lacanobia oleracea. Jackfruit (Artocarpus integrifolia) lectin (jacalin) and black mulberry (Morus nigra) lectin both caused a significant decrease in growth of the peach potato aphid (Myzus persicae) when compared to controls in an artificial diet based bioassay. Interactions of lectins with insect gut tissues in vivo were studied by immunolocalisation. Binding of the snowdrop lectin (Galanthus nivalis agglutinin;GNA) and jack bean (Canavalia ensifomiis) lectin (Concanavalin A; Con-A) to the digestive tract of L oleracea larvae was observed and localised at the electron microscope level after oral ingestion of the proteins. GNA was also observed to bind to the midgut of the two-spot ladybird Adalia bipunctata. No disruption of the brush border membrane of either L oleracea or A. bipunctata was observed. Binding of GNA to the peritrophic membrane of L. oleracea was observed by fluorescence microscopy. Histological evidence of lectin binding to insect guts in vivo was corroborated by in vitro studies, which showed that the lectins GNA and Con- A bind to sections of the digestive tract of L. oleracea larvae. Binding of Con-A to proteins from brush border membranes, solubilised brush border membranes and peritrophic membranes was also observed. The use of confocal microscopy showed that GNA bound to the midgut and haemocytes of the peach potato aphid Myzus persicae, both when incubated with isolated tissues and cells and when fed orally to live insects, providing evidence for transport of GNA across the gut wall. Larvae of L.oleracea fed the lectins GNA and PHA showed a significant increase in polyphenoloxidase levels within the haemolymph, suggesting that the lectins were causing systemic responses in the insects. A partial sequence for leucine aminopeptidase a potential receptor for lectin binding was obtained from a cDNA library constructed from the midgut of the tomato moth larvae.
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Fontinopoulou, Angeliki. "Investigating the glycosylation of recombinant glycoproteins with lectins". Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432779.
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Nantwi, Paul Kwasi Kankam. "Lectins in drug delivery to the oral cavity". Thesis, University of Portsmouth, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.482091.
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Lectins are proteins or glycoproteins of non-immune origin, capable of specific interaction with, and reversible binding to carbohydrate moieties of complex glycoconjugates. Lectins are ubiquitous in nature and are present in all living organisms. In nature lectins are implicated in cell recognition and adhesion processes, and have been described as "second generation" mucoadhesives. The aim of this project was to identify lectins that could be incorporated into dosage forms to allow their retention within the oral cavity. This would allow prolonged localised drug delivery. Initial screening studies on human buccal cells, usmg the avidin-biotincomplex/ diaminobenzidine method suggested that all the lectins tested appeared to bind to varying degrees, as visualised by a diaminobenzidine (DAB) precipitate to the oral epithelial surface. The stain intensities were analysed semi-qualitatively with E micro densitometer GN5 (Barr and Stroud). A substantial reduction in lectin binding was observed after exposing buccal cells to a series of lectin solutions pre-treated with secretor and non-secretor saliva. However when bound to the buccal cells, there was little displacement of lectins on exposure to either saliva types. Kinetic binding studies revealed the presence of the lectins from Pisum sativum and Arachis hypogaea, after only 20 s contact. There were some differences in lectin binding evident between rat oral tissue and human buccal cells, but those that bound avidly to both were selected for furthe studies. In order to allow a quantitative assessment of binding, the lectins from Canavali ensiformis, Arachis hypogaea and Triticum vulgaris were labelled with Technetium-99n (Tc-99m) using a cyclic diethylenetriamine pentaacetic acid conjugation technique. In this preliminary study it was found that 1.18 fmoles of the Canavalia ensiformis lectir 3.27 fmoles of the Arachis hypogaea lectin and 11.11 fmoles of the Triticum vulgari lectin bound per buccal cell. This was reduced when Tc-99m-labelled Canavali ensiformis lectin was inhibited by the presence of 40% w/v glucose solution. It was estimated that a therapeutic dose of a potential dosage form could be conjugated to the Triticum vulgaris lectin within the oral cavity, thus demonstrating the feasibility of using this, and possibly other lectins in a drug delivery strategy. Preliminary in vivo studies in the conscious rat model suggested that the Tc-99m-labelled Canavalia ensiformis an Triticum vulgaris lectins were present within the oral cavity, 1 hand 2 h respectively after application, with about 25% of the Canavalia ensiformis lectin being lost into the stomach through swallowing. Transmission electron microscopy studies were initiated to determine the exact sites of lectins binding to the human buccal cell. Fresh, unfixed human buccal cells were incubated in a solution containing 20 nm gold-labelled Canavalia ensiformis lectin. was found that after processing, the lectin bound to the external surface of the buccal cells, or to external mucin. No binding was observed when pre-fixed human buccal cells were used, indicating that fixation affects the glucose/ mannose-containing binding site Canavalia ensiformis lectin binding to the buccal cells was partially inhibited by the presence of glucose, the hapten sugar. It was concluded that lectins will bind to the rat oral epithelial and human buccal cell surfaces to varying degrees, and will persist, even in the presence of saliva. In particular the lectin from Triticum vulgaris was shown to have good stability in the conscious rat model for up to 2 h, and shows great promise for use in a potential lectin-containing drug delivery system.
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Renney, Charles M. "Novel synthetic lectins for carbohydrate recognition in water". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686165.
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Carbohydrate recognition in water still remains one of the most challenging tasks for supramolecular chemists. Despite the challenges, the Davis group has had good success in designing and synthesising compounds capable of carbohydrate recognition. Within this body of work 6 novel carbohydrate receptors are reported, based upon the anthracene design shown below. The majority of the reported receptors displayed good to excellent affinities to all-equatorial carbohydrates. One of the synthesised receptors, containing methoxy functionality on the anthracene units, demonstrated remarkably high affinity to maltodextrins, such as maltotriose and maltotetraose (Chapter 2). The binding affinities displayed towards maltodextrins by this receptor, ~2000 M-1, are amongst the highest affinities reported for synthetic carbohydrate receptors in water, and they also are of a similar magnitude to the binding affinities displayed by natural carbohydrate receptors, lectins. A selection of unsymmetrical receptors were also synthesised, wherein one anthracene moeity was unsubstituted and the other was substituted with either bromines, methylesters or carboxylic acids (Chapter 3). These designs were implemented in order to red-shift the receptor's fluorescence emission wavelength, something they did achieve, however only at the consequence of a reduced increase in the receptor's fluorescence intensity upon carbohydrate binding. Of the unsymmetrical receptors synthesised, one, containing a tetracarboxylic acid substituted anthracene, displayed exceptional binding to all-equatorial carbohydrates, binding D-glucose with a binding affinity of 186 M-1. This represents the highest binding affinity to glucose reported. Additionally, the receptor displayed a selectivity of 186:1 for glucose over mannose, a selectivity higher than many lectins. One receptor, wherein one anthracene unit was substituted with a naphthalene, displayed no affinity towards carbohydrates in water (Chapter 4). Such a result, highlighted the importance of hydrophobic interactions are in achieving carbohydrate recognition in water. Finally, further investigations into the reported binding of carbohydrates by a porphyrin based system were carried out (Chapter 6). The results showed tight 1:1 binding between the carbohydrate and the porphyrin was absent, and instead kinetically slow readjustments of porphyrin aggregates appeared to be responsible for the change in UV-vis and fluorescence properties of the porphyrin.
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Kaspar, Amir Shermila. "Synthetic lectins with ethylene spacers recognition in water". Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738277.
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Zelensky, Alex N. "In silico analysis of C-type lectin domains' structure and properties /". View thesis entry in Australian Digital Theses Program, 2004. http://thesis.anu.edu.au/public/adt-ANU20050318.185314/index.html.
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Thesis (Ph.D.)--Australian National University, 2004."This CD contains the software (mostly written in Perl) used for comparative structure analysis reported in Chapter 4 (str_comp directory), and for the CTLD database system described in Chapter 2 (CTLD_DB directory)."
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Defaus, Fornaguera Sira. "Glycoprobes for capture and identification of lectins from biological sources". Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/277290.
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Glycosylation is a posttranslational modification affecting the fast majority of cellular surfaces through glycolipids and glycoproteins. It has been estimated that over 80% of all proteins are glycosylated and that the glycans decorating the periphery of these molecules are fundamental for the biological function of the entity. Many of these functions have yet to be unraveled. As the modification is a secondary-gene event, it depends on the availability and activity of a set of glycosyltransferases, the availability of both donor and acceptor substrate (both in time and place), as well as many other factors that may include temperature, pH, etc. As a consequence a single glycosylation site may express a certain number of different glycans, i.e., structural microheterogeneity. The importance of glycosylation as primary mediators of cellular communication, protein-protein cross-talk, and even cell-pathogen interaction has been attributed precisely to this phenomenon.
In the past few years substantial advancements have been made in the understanding of the function of particular glycosidic epitopes, such as the most relevant blood group antigens ABO, and Sda, (sialyl)Lewisx,y,a,b, the HNK-1 antigen, etc., but many more structures have been identified without an attributed functionality, either as a stand-alone epitope or in conjunction with the underlying peptide structure. Similarly, a serious lack of knowledge still exists on the carbohydrate recognizing molecules, i.e. lectins and their function; even so they have been recognized over the last decades as decisive players in numerous biological processes, ranging from cell-cell communication, fertilization, pathogen-cell adhesion to metastasis. Both deficiencies are directly related to the absence of proper tools to elaborate well-defined carbohydrate epitopes for the study of their interaction characteristics and their employment in the discovery of new complementary molecules. Consequently, there is an increasing interest in finding powerful and nanosized tools to screen for these molecules and to study their carbohydrate interactions in detail.
In this Thesis, two complementary approaches are described to characterize lectin-carbohydrate interactions with high sensitivity, low sample consumption, and without the need for sample labeling: SPR and CREDEX-MS. In SPR, we have developed an approach where the sugar is immobilized onto a sensor surface through a tailor-made peptide module that allows (1) to capture the lectin, (2) to characterize the interaction through kinetic and thermodynamic parameters, and (3) to identify the interacted protein by mass spectrometry. In CREDEX-MS, based on proteolytic excision of protein-carbohydrate complexes and mass spectrometric analysis, the peptides conforming the carbohydrate binding domain are identified.
After completing a preliminary phase where the above mentioned methodologies are optimized and used for the study of carbohydrate-protein interactions using purified well-known lectins; the established platforms are employed to analyze carbohydrate-driven interactions in more complex systems. Specifically, SPR and CREDEX-MS techniques are applied in a research project on molecular aspects of reproduction with the main objective of disclosing the molecular elements that participate in the first steps of fertilization in bovine species, namely: formation of the sperm reservoir in the oviductal epithelium and gamete recognition (oocyte (ZP)-sperm interaction).La glicosilació, el procés enzimàtic que uneix sacàrids per produir glicans que s'adhereixen a proteïnes, lípids o altres molècules biològiques, és una modificació co-traduccional i post-traduccional present a la pràctica totalitat de components cel•lulars, on trobem glicoproteïnes, glicolípids i altres glicoderivats. Pel que fa específicament a les proteïnes, s’estima que més d’un 80% estan glicosilades i que aquests glicans són fonamentals en processos biològics com la senyalització cel•lular, el cicle infecciós de certs patògens, les respostes inflamatòria i immune, la fertilització, etc. En els últims anys s’ha avançat substancialment en el coneixement bàsic de la funció de determinats epítops o cadenes glicosídiques concretes. No obstant, es desconeixen les funcions de moltes altres estructures glicosídiques. D’altra banda, també existeix un cert desconeixement sobre les molècules que reconeixen els carbohidrats, les lectines “lectores del codi glicòmic”. Aquestes proteïnes es caracteritzen per reconèixer i unir-se de forma reversible i específica a certs monosacàrids o epítops oligosacàrids donant lloc a interaccions similars a les reaccions antigen-anticòs o enzim-substrat. El paper de les lectines en processos com l'aglutinació i la definició de grups sanguinis, la inflamació (selectines), la mielinització del teixit nerviós, la progressió tumoral, etc., demostra la ubiqüitat i diversitat d'activitats en què es veuen implicades aquestes proteïnes. Per això, disposar d'una eina ràpida i fiable per al seu aïllament i identificació, previ a l'estudi de les seves interaccions amb polisacàrids, constitueix un objectiu de màxim interès en l'actual investigació biomèdica. En la present Tesi Doctoral, es descriuen dues aproximacions complementàries mitjançant les quals es poden caracteritzar les interaccions lectina-carbohidrat amb gran sensibilitat, poca mostra i sense la necessitat de cap marcatge. En la tècnica de ressonància de plasmó superficial (SPR), el sucre és immobilitzat sobre una superfície a través d'un mòdul peptídic, la qual cosa permet (1) capturar la lectina, (2) caracteritzar la seva interacció mitjançant paràmetres cinètics i termodinàmics i (3) identificar posteriorment la proteïna mitjançant espectrometria de masses. Complementàriament, la tècnica CREDEX-MS, basada en l'excisió proteolítica del complex proteïna-sucre i posterior anàlisi per espectrometria de masses, ens permet identificar els pèptids que formen part del domini d'unió al sucre.
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Tajra, FÃbio Solon. "Biotechnological potential of the red marine alga Hypnea musciformis (HML) applied to Dentistry". Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5285.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoDental Caries is an infectious disease naturally multi-factorial that begins in the childhood, able to spread its intensity and prevalence according to the mouth ambient conditions of each host. The risk of the patients to develop, in some time of their lives, carious lesions can be measured through a complex analysis using health determinant factors and other specific factors of the health-disease process. Since the dental caries forward diagnostic as well as the review of the auxiliary determinant factors of the dental caries danger evaluation, the treatment becomes simpler, less invasive and costing lower. It has been quite broad-casted lately the use of lectins to diagnose and to prevent some diseases. When dealing with dental caries disease, through many years this strategy has been explored still inceptively. Looking through this perspective, the goal of this trial was to investigate the biotechnological potential of the red marine alga Hypnea musciformis (HML) applied to Dentistry. It is about an explanatory-experimental study of quantitative approach through the health questionnaire and data statistics analysis. The research makes reference to some comparative analysis of salivary tests and the cariogenic activity in twelve year-old students and it searches to evaluate the biotechnological potentialities of the lectin from the red marine alga Hypnea musciformis (HML) in the diagnose and prevention of the dental caries. The concentration area of this trial was the macromolecules/ lectin biotechnological application. In the present trial were compared obtained results through the application of the conventional clinical exams to dental caries and salivary tests of dental caries activity pointed by the CARIOGRAMÂ program in association with lab analysis using specific lectins. From this trial, it has been concluded that, about lectins as a biotechnological potential to prevention and diagnose of the dental caries, it has been noticed that there is recognition of resident glycoconjugate on pacifier saliva of high and low risk observed in immunofluorescence pattern. The results showed that the tested lectin has the capacity to intervene on the bacterial growth in a negative way, it is being distinguished statistically (p<0,01) in relation to control group of saline and BSA. However, inhibition studies of the microbial biofilms using the HML are being programmed to evaluate the using possibility of these protein as biotech input to be used for dental caries prevention. It could be said also that the obtained results by the use of HML in the antimicrobial activity were promising, showing that this lectin has presented antimicrobial activity even on very small amounts. As to the use of these protein in the biofilm formation and developing there was no characteristic pattern.
A cÃrie à uma doenÃa infecciosa de natureza multifatorial que se inicia na infÃncia, podendo aumentar de intensidade e prevalÃncia de acordo com as condiÃÃes do ambiente bucal de cada hospedeiro. O risco do paciente em desenvolver, em algum perÃodo de seu ciclo de vida, lesÃes cariosas pode ser medido atravÃs de uma anÃlise complexa que utiliza os fatores determinantes da saÃde e outros fatores especÃficos do processo saÃde-doenÃa. A partir do diagnÃstico precoce da doenÃa cÃrie, assim como anÃlise dos fatores determinantes auxiliares da avaliaÃÃo do risco de cÃrie, o tratamento torna-se mais simples, menos invasivo e de menor custo. Tem sido bastante difundida ultimamente a utilizaÃÃo de lectinas para diagnÃstico e prevenÃÃo de algumas doenÃas. Em se tratando da doenÃa cÃrie, ao longo de muitos anos, essa estratÃgia tem sido explorada ainda de forma incipiente. Nesta perspectiva, o objetivo deste trabalho foi investigar as potencialidades biotecnolÃgicas da lectina de alga marinha da espÃcie de Hypnea musciformis (HML) aplicadas à odontologia. Trata-se de um estudo explicativo-experimental de abordagem quantitativa atravÃs de questionÃrio de saÃde e anÃlises estatÃsticas de dados. A pesquisa faz referÃncia à uma anÃlise comparativa de testes salivares e atividade cariogÃnica em escolares de 12 anos de idade e a busca avaliar as potencialidades biotecnolÃgicas da lectina de alga marinha da espÃcie de Hypnea musciformis (HML) no diagnÃstico e prevenÃÃo de cÃrie dentÃria. A Ãrea de concentraÃÃo deste estudo MacromolÃtulas / AplicaÃÃo BiotecnolÃgica de Lectinas. No presente estudo, foram comparados os resultados obtidos atravÃs da aplicaÃÃo de exame clÃnico convencional para cÃrie e testes salivares de atividade cariogÃnica apontados pelo programa CARIOGRAM em associaÃÃo com anÃlises laboratoriais com a utilizaÃÃo de lectinas especÃficas. A partir deste estudo, concluiu-se que, em se tratando do uso de lectinas como potencial biotecnolÃgico para a prevenÃÃo e diagnÃstico de cÃrie dentÃria, percebeu-se que hà reconhecimento de glicoconjugados presentes na saliva de pacientes de alto e baixo risco observados em padrÃo de fluorescÃncia. Os resultados demonstram que a lectina testada tem a capacidade de interferir no crescimento bacteriano de forma negativa, sendo estatisticamente significante (p<0,01) em relaÃÃo aos grupos controle de salina e BSA. Entretanto estudos de inibiÃÃo da formaÃÃo de biofilmes microbianos utilizando a HML estÃo sendo programados, para assim avaliar a possibilidade de utilizaÃÃo dessas proteÃnas como insumos biotecnolÃgicos a ser utilizados para prevenÃÃo da cÃrie dentÃria. Pode-se ainda afirmar que os resultados obtidos pelo uso de HML na atividade antibacteriana foram promissores, mostrando que esta lectina apresentou atividade antibacteriana mesmo em quantidades muito pequenas. Quanto ao uso destas proteÃnas na formaÃÃo e desenvolvimento de biofilmes, nÃo houve padrÃo caracterÃstico.
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Correia, Jorge Luis Almeida. "PurificaÃÃo, caracterizaÃÃo parcial e potencialidade biotecnolÃgica de trÃs lectinas de sementes de espÃcies de Leguminosae da subtribo Diocleinae". Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17238.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorFundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Leguminosae is recognized by the large amount of isolated and characterized lectins, especially seeds. In this group stand out proteins extracted from species belonging to subtribe Diocleinae, the number of studies in different areas of knowledge. Lectins can be defined as proteins or glycoproteins which are not originated from a body's immune response and have the ability to recognize and bind reversibly to mono or oligosaccharides particular without, however, altering their chemical structures. Different works in our group are structurally haracterizing these proteins as well as elucidating some possible biotechnological applications for these molecules. In this sense, the objective of this study was to isolate and characterize lectins of different species of Leguminosae of Diocleinae subtribe and test them for toxicity to Artemia sp. naupilos, The effect on the smooth muscle of blood vessels and the detention lectin matrix agarose previously activated with cyanogenic bromide (CNBr). Were isolated and characterized the lectin Dioclea sclerocarpa, Dioclea lasiocarpa and Dioclea lasiophylla. Were also made circular dichroism studies on lectin Dioclea sclerocarpa and Dioclea lasiocarpa. The lectin Dioclea lasiophylla was tested against Artemia sp. order to assess their toxicity and was also immobilized on agarose matrix. We evaluated the effect of lectin Dioclea lasiocarpa in the smooth muscle of blood vessels. The knowledge gained from the three scientific articles published in this thesis is a major breakthrough in this promising field of study that has been continuously growing for biotechnological applications.
A famÃlia Leguminosae à reconhecida pela grande quantidade de lectinas isoladas e caracterizadas, especialmente de sementes. Neste grupo se destacam as proteÃnas extraÃdas de espÃcies pertencentes a subtribo Diocleinae, pela quantidade de estudos em diferentes Ãreas do conhecimento. Lectinas podem ser definidas como proteÃnas ou glicoproteÃnas que nÃo sÃo originadas a partir de uma resposta imunolÃgica do organismo e possuem a capacidade de reconhecer e se ligar reversivelmente a mono ou oligossacarÃdeos especÃficos sem, no entanto, alterar suas estruturas quÃmicas. Diferentes trabalhos no nosso grupo vÃm caracterizando estruturalmente essas proteÃnas, bem como elucidando algumas possÃveis aplicaÃÃes biotecnolÃgicas para essas molÃculas. Neste sentido, o objetivo deste trabalho foi isolar e caracterizar lectinas de diferentes espÃcies de Leguminosae da subtribo Diocleinae e testa-las com relaÃÃo à toxicidade para naupilos de Artemia sp., o efeito na musculatura lisa de vasos sanguÃneos e a imobilizaÃÃo de lectina em matriz de agarose previamente ativada com brometo cianogÃnico (CNBr). Foram isoladas e caracterizadas as lectinas de Dioclea sclerocarpa, Dioclea lasiocarpa e Dioclea lasiophylla. TambÃm foram feitos estudos de dicroÃsmo circular na lectina de Dioclea sclerocarpa e Dioclea lasiocarpa. A lectina de Dioclea lasiophylla foi testada contra Artemia sp.de forma a avaliar sua toxicidade e tambÃm foi imobilizada em matriz de agarose. Foi avaliado o efeito da lectina de Dioclea lasiocarpa na musculatura lisa de vasos sanguineos. O conhecimento acumulado a partir dos trÃs artigos cientÃficos publicados nesta tese constitui um grande avanÃo no neste campo promissor de estudo que vem em contÃnuo crescimento para aplicaÃÃo biotecnolÃgica.
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Sun, Yedi. "Novel Functionalized Lectins Engineered by Affinity-Guided DMAP Chemistry". 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174964.
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Gemma, Emiliano. "Synthesis of Oligosaccharides for Interaction Studies with Various Lectins". Doctoral thesis, Stockholm : Department of Organic Chemistry, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-459.
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Banchonglikitkul, Chuleratana. "Lectins in drug delivery to the eye and mouth". Thesis, University of Portsmouth, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323275.
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