Dissertations / Theses on the topic 'DPPZ'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'DPPZ.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Derrat, Hanan S. "Organic and metal organic cationic DNA intercalators based on DPPZ analogues." Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574605.
Full textDyer, Joanne. "Designing infrared probes of DNA based on rhenium tricarbonyl DPPZ complexes." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289455.
Full textMadureira, João Paulo Lopes. "Complexos de ruténio com ligandos politioéteres e/ou polipiridílicos : síntese, caracterização estrutural e interacção com o ADN." Doctoral thesis, Universidade de Aveiro, 2005. http://hdl.handle.net/10773/15264.
Full textNesta tese são apresentados perto de quatro dezenas de novos complexos de ruténio(II), em cuja esfera de coordenação estão simultaneamente presentes um politioéter macrocíclico e um ligando polipiridílico. Os complexos sintetizados possuem as fórmulas genéricas [Ru([9]anoS3)(N-N)Cl]+ ou [Ru([12]anoS4)(N-N)]2+, em que [9]anoS3 é 1,4,7-tritiociclononano, [12]anoS4 é 1,4,7,10-tetratiociclododecano e N-N representa um ligando polipiridílico. Estes últimos foram seleccionados entre ligandos disponíveis comercialmente, de síntese conhecida da literatura, ou ainda entre novos derivados de dipirido[3,2-a:2’,3’-c]fenazina (ddpz). Os novos derivados de dppz foram concebidos com base numa das seguintes alternativas: i) expansão directa da superfície aromática; ii) acoplamento formal de pteridinas a uma unidade fenantrolina e iii) formação de ligações covalentes C-C entre dppz e grupos poliaromáticos. Foram também sintetizados duas dezenas de complexos de ruténio(II) em cuja esfera de coordenação se incluem macrociclos do tipo politioéter ou poliamina e variados ligandos monodentados, tais como halogenetos, dmso, MeCN, ou ligandos de azoto monocoordenados, como imidazol, indazol ou pirazol. Os diversos ligandos e complexos foram caracterizados por numerosas técnicas: infravermelho, Raman, RMN, absorção molecular, luminescência, espectrometria de massa (ES, FAB, EI), voltametria linear ou cíclica, espectroelectroquímica de UV/Vis/NIR ou de EPR, condutimetria, difracção de raios-X, microscopia electrónica de varrimento, ou análises elementares, para além de terem sido realizados cálculos teóricos auxiliares. Foi também estudado o comportamento em meio aquoso de alguns dos complexos sintetizados, assim como foi testada a capacidade de alguns dos complexos com ligandos polipiridílicos em interactuarem com o ADN. Para isso foram realizados ensaios de denaturação térmica, titulações de UV/Vis e estudos de luminescência em estado estacionário.
Nearly forty new ruthenium(II) complexes have been synthesised, with both polythioether macrocycles and polypyridyls present on the coordination sphere. The synthesised complexes have the general formula [Ru([9]aneS3)(N-N)Cl]+ or [Ru([12]aneS4)(N-N)]2+, where [9]aneS3, [12]aneS4, and N-N represents 1,4,7-trithiacyclononane, 1,4,7,10-tetrathiacyclododecane, and a polypyridyl ligand, respectively. N-N ligands have been selected from commercially available products, literature known compounds, and dipyridophenazine (dppz) new ligands, presented on this thesis. The new dipyridophenazine derivatives were designed with three different strategies: i) direct aromatic surface expansion; ii) pteridine formal coupling to a phenanthroline unit; and iii) C-C covalent bond formation between dppz and polyaromatic groups. Twenty ruthenium(II) complexes with a coordination sphere composed of a polythioether or polyamine macrocycle and several monodentate ligands (ex: halogens, dmso, MeCN and nitrogen heterocyles, as imidazole, indazole or pyrazole) have also been prepared. The ligands and complexes have been characterised by several techniques, namely: infrared, Raman, NMR, UV/Vis, luminescence, mass spectrometry (EI, ES, FAB), cyclic or linear voltammetry, UV/Vis/NIR and EPR spectro-electrochemistry, conductivity, X-ray diffraction, SEM, micro-analysis and theoretical calculations. Some of the complexes have been studied on aqueous or organic solutions in order to evaluate their reactivity and determine their formula on that media. Several polythioether-polypyridyl ruthenium complexes have been tested in order to evaluate theirs DNA interaction capability. The studies were conducted by UV/Vis titration, steady-state luminescence and thermal denaturation.
Ergun, Seza. "Structural And Functional Investigation Of The Interaction Of Agomelatine With Model Membranes." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614997/index.pdf.
Full textSouza et al., 2009). These results may indicate that agomelatine is partially buried in the hydrocarbon core of the bilayer, interacting primarily with the C2-C8 methylene region of the hydrocarbon chains. All these results highlight the fact that agomelatine interacts around the head group in such a manner that it destabilizes the membrane architecture to a large extent.
Cafe, Peter F. "Towards reliable contacts of molecular electronic devices to gold electrodes." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/3870.
Full textCafe, Peter F. "Towards reliable contacts of molecular electronic devices to gold electrodes." University of Sydney, 2008. http://hdl.handle.net/2123/3870.
Full textSYNOPSIS OF THIS THESIS The aim of this thesis is to more fully understand and explain the binding mechanism of organic molecules to the Au(111) surface and to explore the conduction of such molecules. It consists of five discreet chapters connected to each other by the central theme of “The Single Molecule Device: Conductance and Binding”. There is a deliberate concentration on azine linkers, in particular those with a 1,10-phenanthroline-type bidentate configuration at each end. This linker unit is called a “molecular alligator clip” and is investigated as an alternative to the thiol linker unit more commonly used. Chapter 1 places the work in the broad context of Molecular Electronics and establishes the need for this research. In Chapter 2 the multiple break-junction technique (using a Scanning Tunnelling Microscope or similar device) was used to investigate the conductance of various molecules with azine linkers. A major finding of those experiments is that solvent interactions are a key factor in the conductance signal of particular molecules. Some solvents interfere with the molecule’s interaction with and attachment to the gold electrodes. One indicator of the degree of this interference is the extent of the enhancement or otherwise of the gold quantized conduction peak at 1.0 G0. Below 1.0 G0 a broad range for which the molecule enhances conduction indicates that solvent interactions contribute to a variety of structures which could bridge the electrodes, each with their own specific conductance value. The use of histograms with a Log10 scale for conductance proved useful for observing broad range features. vi Another factor which affects the conductance signal is the geometric alignment of the molecule (or the molecule-solvent structure) to the gold electrode, and the molecular alignment is explored in Chapters 3 for 1,10-phenanthroline (PHEN) and Chapter 4 for thiols. In Chapter 3 STM images, electrochemistry, and Density Functional Theory (DFT) are used to determine 1,10-phenanthroline (PHEN) structures on the Au(111) surface. It is established that PHEN binds in two modes, a physisorbed state and a chemisorbed state. The chemisorbed state is more stable and involves the extraction of gold from the bulk to form adatom-PHEN entities which are highly mobile on the gold surface. Surface pitting is viewed as evidential of the formation of the adatom-molecule entities. DFT calculations in this chapter were performed by Ante Bilic and Jeffery Reimers. The conclusions to Chapter 3 implicate the adatom as a binding mode of thiols to gold and this is explored in Chapter 4 by a timely review of nascent research in the field. The adatom motif is identified as the major binding structure for thiol terminated molecules to gold, using the explanation of surface pitting in Chapter 3 as major evidence and substantiated by emergent literature, both experimental and theoretical. Furthermore, the effect of this binding mode on conductance is explored and structures relevant to the break-junction experiment of Chapter 2 are identified and their conductance values compared. Finally, as a result of researching extensive reports of molecular conductance values, and having attempted the same, a simple method for predicting the conductance of single molecules is presented based upon the tunneling conductance formula.
Zbořilová, Hana. "Studium membránových vlastností liposomálních systémů pomocí fluorescenční spektroskopie." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449373.
Full textChi, Danny T., and Nien-Lou Li. "DPPM Optical Communications and Reed-Solomon Codes." International Foundation for Telemetering, 1992. http://hdl.handle.net/10150/608918.
Full textPulse position modulation (PPM) has many attractions for optical communication over deep space and for intersatellite communications. This paper describes a variate of PPM, known as differential pulse position modulation (DPPM) which can double the data throughput relative to PPM. We begin this paper with a survey of various laser sources and laser modulation techniques used in modem space optical communications. We then discuss the advantages of the combination of DPPM and Reed-Solomon (RS) codes.
López-Amaya, Clara Inés. "Interaction of Candida rugosa lipase with DPPC liposomes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq27441.pdf.
Full textKell, Henny. "Wechselwirkung des Lipoheptapeptides Surfactin mit Lipiddoppelschichten aus DMPC und DPPC." [S.l.] : [s.n.], 2006. http://opus.kobv.de/tuberlin/volltexte/2007/1463.
Full textCigánek, Martin. "Syntéza a studium nových derivátů diketopyrrolopyrrolů (DPPs) pro organickou elektroniku." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316170.
Full textSilva, Mauro Marcos da. "Estudo da composição Química do óleo essencial de Lippia microphylla CHAM em três anos diferentes e atividade antioxidante." Universidade Federal de Roraima, 2014. http://www.bdtd.ufrr.br/tde_busca/arquivo.php?codArquivo=249.
Full textO estado de Roraima é dividido em três grandes sistemas ecológicos: floresta, campinas-campinarana e savanas ou cerrados e está localizado no extremo norte da Amazônia brasileira. Apesar da grande variedade de plantas existem poucas informações sobre plantas aromáticas da região. Lippia microphylla Cham., pertence à família Verbenaceae e ao gênero Lippia, e conhecida popularmente em Roraima como salva do campo, sendo encontrada nos lavrados roraimenses. Esta planta pode ser encontrada com facilidade ao longo da BR 174 que liga Boa Vista a Santa Elena de Uairén, na Venezuela. O objetivo desse trabalho foi avaliar a constituição química do óleo essencial de Lippia microphylla Cham. em épocas e horários diferentes e analisar sua atividade antioxidante. As amostras foram coletadas no município de Boa Vista, Roraima, em três horários diferentes (8,12 e 18 horas) nos meses de maio 2009, 2010 e 2011. As folhas extraídas por hidrodestilação com auxílio de um aparelho de clevenger e os óleos foram analisados por cromatografia gasosa com auxílio da espectrometria de massas. Para determinação da atividade antioxidante do óleo essencial foi utilizado o método de capacidade sequestrante do radical livre DPPH. Os maiores rendimentos de óleos foram registrados em maio de 2011, mês que registrou maior precipitação, mas não choveu no dia da coleta. A análise da constituição do óleo revelou que o timol, carvacrol, E-cariofileno, nerolidol e o óxido de cariofileno foram os principais constituintes, sendo o carvacrol majoritário em quase todas as análises. O óleo de melhor capacidade antioxidante foi extraído do material coletado ao meio dia e contem maior concentração de timol (9,22%) e carvacrol (19,80%). Observamos que os óleos coletados nos diferentes anos apresentam diferenças significativas quanto a sua composição química e ao seu rendimento. A chuva do dia da coleta foi mais relevante do que o volume de precipitação no mês. A atividade antioxidante desses óleos pode ser atribuída principalmente à presença dos dois isômeros fenólicos.
The state of Roraima is divided into three major ecological systems: forests, meadow-campinarana and savannas, and are located in the extreme north of the Brazilian Amazon. Despite the wide variety of plants there is little information on herbs of the region. The Lippia microphylla Cham., belongs to the family Verbenaceae and the genus Lippia, popularly known as salva-do-campo being found in the Roraima savannas. This plant is easily found along the margins of the BR 174, the route Boa Vista, Brazil, to the Santa Elena de Uairén, Venezuela. The aim of this study was to evaluate the chemical composition of essential oil of Lippia microphylla Cham. Collected at different times and schedules and analyze their antioxidant activity. The samples were collected in Boa Vista, Roraima, at three different times ( 8, 12 and 18 hours ) in May 2009, 2010 and 2011, for realization of antioxidant activity the samples were collected in the month of March 2011. The leaves were extracted by hydrodistillation with the assistance of a Clevenger apparatus and the oils analyzed by Gas chromatography coupled with mass spectrometry, GC-MS. To determine the antioxidant activity of the essential oil the method of sequestering ability of the free radical DPPH was used. The highest yields of oils were recorded in May 2011, which recorded highest rainfall month, but it did not rain on the day of collection. The analysis of the constitution of the oils revealed that thymol, carvacrol, E-caryophyllene, nerolidol and caryophyllene oxide were the main constituents of which the majority carvacrol was in almost all analyzes. The best antioxidant capacity oil was extracted from material collected at noon containing higher concentration of thymol ( 9.22% ) and carvacrol ( 19.80% ). We observed that the oils collected in different years showed significant differences in their chemical composition and yield. The rain on the day of collection was more important than the volume of rainfall in the month. The antioxidant activity of these oils can be attributed mainly to the presence of two phenolic isomers.
Morton, Colin J. H. "Novel derivatives of DPP and related heterocycles." Thesis, University of St Andrews, 1999. http://hdl.handle.net/10023/15291.
Full textPonsot, Flavien. "Hybrides bactériochlorine-dicétopyrrolopyrrole (DPP) : Nouveaux fluorophores proche infrarouge pour des applications en biodétection/bioimagerie." Thesis, Bourgogne Franche-Comté, 2020. https://nuxeo.u-bourgogne.fr/nuxeo/site/esupversions/1fa27cab-663e-4192-be47-cd34a712a1cd.
Full textNear-infrared (700-900 nm) absorbing and emitting organic-based fluorophores are valuable tools for bioimaging applications. Indeed, biological component absorption, diffusion and autofluorescence are quite low in this region (known as the first therapeutic window NIR-I), making tissues relatively transparent to these long wavelengths. Bacteriochlorins are porphyrins derivatives in which two double bonds are reduced. These molecules display a strong absorption and emission within NIR-I spectral range. DPPs are structurally simpler fluorophores displaying very interesting properties. They have high fluorescence quantum yields, are highly (photo)chemically and thermally stable. The aim of this thesis is to associate these two fluorophore units in order to yield novel multi-chromophoric molecular architectures that combine their complementary properties. DPP dyes used in the design of the hybrids are highly versatile. They can be used as fluorogenic reporters for the detection of relevant enzymatic activities in the biological media by introducing a specific triggering unit of the targeted analyte and water-solubilizing moieties
Coat, Françoise. "Elaboration et proprietes de chaines de carbone inorganique stabilisees par les groupements terminaux (c#5me#5)(dppe)fe(ii) et (c#5me#5)(dppe)fe(iii)." Rennes 1, 1995. http://www.theses.fr/1995REN10141.
Full textLE, STANG SYLVIE. "Nouveaux composes modeles pour l'electronique moleculaire en serie cp*fe(dppe)-c 2-x-c 2-fe(dppe)cp* n + (n = 0 2, x = heterocycles aromatiques)." Rennes 1, 2000. http://www.theses.fr/2000REN10038.
Full textda, Cunha Amaral Lima Danielle. "Estudo comparativo da atividade antioxidante de plantas medicinais da caatinga utilizadas como antiinflamatórias." Universidade Federal de Pernambuco, 2011. https://repositorio.ufpe.br/handle/123456789/3324.
Full textPlantas com atividade antioxidante podem estar envolvidas no tratamento e/ou prevenção de diversas enfermidades, em especial as que envolvem processos inflamatórios. Foram selecionadas vinte espécies de plantas utilizadas para tratar inflamação pela comunidade de Carão, localizada em Altinho-PE, e dezenove espécies de forma aleatória. A coleta foi realizada na referida região no mês de setembro de 2009, de no mínimo 3 indivíduos de cada espécies, submetidas a extração por maceração com metanol 80% durante 6 dias e evaporado o solvente sob pressão reduzida. Buscando avaliar a correlação entre métodos utilizados para determinar a atividade antioxidante foram aplicados três: atividade sequestrante de radical livre DPPH (DPPH), ensaio da atividade quelante do íon ferroso (FIC) e poder antioxidante redutor férrico (FRAP). Avaliou-se também o poder antioxidante de espécies utilizadas para tratamento de inflamações comparadas às espécies selecionadas de forma aleatória. Observou-se que não houve correlação entre os métodos FIC e DPPH (rs = -0,3008 e p = 0,1975) e entre FIC e FRAP (rs = 0,3042 e p = 0,1921). Entretanto, foi possível observar correlação significativa entre FRAP e DPPH (rs = -0,9563 e p = < 0,0001). Através da análise de variância de Kruskal-Wallis os dois grupos de espécies estudadas foram estatisticamente iguais através dos métodos DPPH e FRAP e que as espécies aleatórias foram estatisticamente mais efetivas quando avaliado o poder quelante do íon ferroso. Contudo, quando utilizada a classificação de Melo et al (2010), observa-se que 45% das espécies antiinflamatórias apresentaram boa atividade seqüestradora de radicais livres comparadas às 36,84% das aleatórias. Conclui-se que os métodos utilizados avaliam a atividade antioxidante por meio de mecanismos distintos, não sendo recomendável o emprego de um único método para determinação da atividade antioxidante. Sendo o método DPPH mais indicado para avaliar a atividade antioxidante de espécies utilizadas para tratar inflamação. Dados sugerem que as espécies anttinflamatórias não agem quelando o íon ferroso, não sendo este método mais indicado para avaliação da atividade antioxidante de espécies antiinflamatórias, visto a quelação de metais de transição tem um papel secundário no mecanismo de inibição dos radicais livres
Tran, Tinh Vi. "The hydrolysis rate of fluorescent dipeptides by dipeptidyl peptidase I (DPPI)." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/10132.
Full textZander, Thomas [Verfasser], and Andreas [Akademischer Betreuer] Schreyer. "The interaction of DPPC and hyaluronan / Thomas Zander ; Betreuer: Andreas Schreyer." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://d-nb.info/1116604590/34.
Full textZander, Thomas Verfasser], and Andreas [Akademischer Betreuer] [Schreyer. "The interaction of DPPC and hyaluronan / Thomas Zander ; Betreuer: Andreas Schreyer." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:18-80661.
Full textPantazis, Periklis. "Role of endocytic trafficking during Dpp gradient formation." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1106665288062-25959.
Full textMamza, Jil Billy. "Comparative effectiveness and safety of DPP-4 inhibitors." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33202/.
Full textPantazis, Periklis. "Role of endocytic trafficking during Dpp gradient formation." [S.l. : s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11611845.
Full textSandrino, Bianca. "Estudo do complexo mer-[RuCl3(dppb)(VPy)]: síntese, caracterização e potenciais aplicações." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2010. http://tede2.uepg.br/jspui/handle/prefix/2086.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
The synthesis of biphosphine complex, specifically containing the unit “[RuCln(dppb)]” (dppb = 1,4-bis(diphenylphosphino) butane), has attracted considerable interest due to applications in catalysis for hydrogenation of organic compounds and more recently in biological activities and modified electrodes due to its stability and promising redox property. Within this perspective, in this work the complex mer-[RuCl3(dppb)(VPy)] (VPy = 4-vinylpyridine), RuVPy was synthesized from the replacement of the aqua ligand of the complex mer-[RuCl3(dppb)H2O] by ligand 4-vinylpyridine in the ratio 1:1.1 (complex / ligand). Spectroscopic results indicated that the incorporation of the ligands dppb and VPy yielded bands at 435, 516, 1002, 1087, 1433 and 1484 cm-1, 262, 390, 450, 530 nm coincident with spectra of the serie complex mer-[RuCl3(dppb)(L)] (N-heterocyclic). Values of g tensor (g1 = 2.40, g2 = 2.00 and g3 = 1.69) confirmed the meridional arrangement of chloride ligands around the octahedral complex geometry. An interesting voltammetric profile was observed for RuVPy solution due to the presence of three peaks with oxidation potential values of 0.07, 0.42 and 0.54 V (vs. Ag/AgCl) that emerged after the reduction of core metallic -0.07 V, attributed to redox processes of complexes [Ru2Cl5(dppb)2], [RuCl2(dppb)(4-VPy)2] and [Ru2Cl4(dppb)2(4-VPy)] formed in solution. Immobilization the RuVPy on different surfaces (LB films, casted film, dip-coated film and carbon paste) revealed only one electrochemical process around 0.55 V (vs. Ag/AgCl) assigned to the redox couple RuII/RuIII. Also, was found that the nature of the nanostructured LB films of RuVpy compared to thick films without structural organization due to the higher peak current compared to the films casted films, dip-coated electrode and carbon paste. The versatility of the RuVpy complex was demonstrated by the conversion of 82.5% of cyclohexene in cyclohexane in the hydrogenation catalysis and the conversion of 91% of cyclooctene in epoxide in the oxidation catalysis. Finally, preliminary catalytic tests showed a lower conversion (67%) in the oxidation of cyclooctene when RuVPy is immobilized on silica.
A síntese de complexos bifosfínicos metálicos, mais especificamente contendo a unidade “[RuCln(dppb)]” (dppb= 1,4-bis(difenilfosfina)butano), tem atraído considerável interesse devido às aplicações em catálise de hidrogenação de compostos orgânicos e mais recentemente em atividades biológicas e eletrodos modificados devido a sua estabilidade e promissora propriedade redox. Dentro desta perspectiva neste trabalho sintetizou-se o complexo mer-[RuCl3(dppb)(VPy)] (VPy= 4-vinilpiridina), RuVPy, a partir da substituição do ligante aqua do complexo mer-[RuCl3(dppb)H2O] pelo ligante 4-vinilpiridina na proporção 1:1,1 (complexo/ligante). Resultados espectroscópicos indicaram que houve a incorporação dos ligantes Vpy e dppb, a partir das bandas em 435, 516, 1002, 1087, 1433 e 1484 cm-1, e 262, 390, 450, 530 nm coincidentes com espectros da série de complexos mer-[RuCl3(dppb)L] (N-heterocíclico). Valores de tensor g (g1= 2,40, g2= 2,00 e g3= 1,69) confirmaram a disposição meridional dos ligantes cloretos ao redor da geometria octaédrica do complexo. Um interessante perfil voltamétrico foi observado para o RuVPy em solução, devido à presença de três picos de oxidação com valores de potenciais em 0,07, 0,42 e 0,54 V (vs Ag/AgCl) que surgiram após a redução do centro metálico em -0,07 V, atribuídos aos processos redox dos complexos [Ru2Cl5(dppb)2], [RuCl2(dppb)(4-VPy)2] e [Ru2Cl4(dppb)2(4-VPy)] formados em solução. Ao imobilizar o RuVPy em diferentes superfícies eletródicas (filmes LB, casted, dip-coated e pasta de carbono) observou-se somente um processo em torno de 0,55 V (vs Ag/AgCl) atribuído ao par redox RuII/RuIII. Além disto, constatou-se a natureza nanoestruturada dos filmes LB do RuVpy em função da maior corrente de pico em relação aos filmes casted, dip-coated e do eletrodo de pasta de carbono. A versatilidade do complexo RuVpy foi demonstrada pela conversão de 82,5% de cicloexeno em cicloexano em catálise de hidrogenação, bem como pela conversão de 91% do cicloocteno em epóxido na catálise de oxidação. Por fim, em testes catalíticos preliminares constatou-se menor conversão (67%) na oxidação do cicloocteno quando o RuVPy é imobilizado em sílica.
Gangadharan, Komala Muralikrishna. "The Role of SGLT2 Inhibitors and DPP4 Inhibitors in Preventing Diabetic Nephropathy." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15925.
Full textMonteiro, Vania Claudia Barros. "Avaliação do estresse oxidativo em humanos e em animais suplementados com ácidos graxos polinsaturados omega-3." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/9/9131/tde-29052007-092628/.
Full textOmega-3 polyunsaturated fatty acids (n-3 PUFA) such as eicosapentaenoic (C20:5 n-3, EPA) and docosahexaenoic (C22:6 n-3, DHA) reduce plasma triacylglycerol concentration in humans. However, higher proportion of these fatty acids in the diet could raise cells lipoperoxidation susceptibility, increasing the cardiovascular disease risk. Although animal models are not recommended to evaluate the effect of n-3 PUFA in plasma lipoproteins, they have been widely used as model for oxidative damage. Difference in methodological proceedings has also caused difficulties to compare data among assays. Thus, the objective of this study was to apply the same methodology to investigate the effect of n-3 PUFA supplementation on oxidative biomarkers in animal and human model. Individuals were randomly assigned in two groups in a parallel double blind design and received a supplement of 460.0 mg/day n-3 PUFA (OMEGA) containing 240.0 mg EPA + 160.0 mg DHA + 60.0 mg other n-3 PUFAs, or soybean oil (PLACEBO) during 6 weeks. Wistar rats were also assigned in two groups and received a diet containing 192.5 mg/day n-3 PUFA (FO) containing 116.3 mg EPA + 61.5 mg DHA + 14.7 mg other n-3 PUFAs or soybean oil (SO) for 3 weeks. Individuals in OMEGA group showed higher malondialdehyde (MDA) concentration in plasma measured by TBARS when compared to their baseline values. N-3 PUFA supplementation did not change plasma α-tocopherol concentration and antioxidant activity determined by DPPH method. Although animals have received a 10-fold higher dose of n-3 PUFA (2.9 mg/ kcal) than humans (0.3 mg/kcal), no alteration was observed between FO and SO groups for plasma and brain homogenate MDA concentration. In summary, it can be suggested that the model used in this study doesn\'t seem appropriate to evaluate oxidative stress after dietetic interventions with n-3 PUFA due to physiological differences involved in lipid metabolism and antioxidant protection observed between both models.
Calomeni, Andressa do Valle. "Utilização de película de amendoim para produção de pigmento natural em pó: estudo do efeito do processo de atomização na estabilidade, propriedades antioxidante e antimicrobiana do material." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/74/74132/tde-03022016-162446/.
Full textThe peanut skin presents intense red color and is rich in phenolic compounds, however the liquid extract is unstable and difficult to commercialize. The aim of this project was to extract the pigments of peanut skin, study the process of spray drying this extract, characterize the powders as well as its antioxidant properties, antimicrobial properties and storage stability, when compared to the control. The extract was characterized measuring the phenolic compounds, pH, moisture, ash, protein, lipids, sugars, aflatoxin and acidity. The extracts were then mixed with the carrier agent at concentrations of 10, 20 and 30%, these were atomized in a spray dryer at inlet air temperatures of 130, 150 and 170 º C. To obtain a control sample, part of the extract was freeze-dried without the presence of maltodextrin. The powders were characterized for moisture, water activity, hygroscopicity, morphology, particle size, color, total phenolic content, solubility, stability, antimicrobial and antioxidant properties by the methods: ORAC, DPPH and ABTS HPLC-online. In the analysis of the liquid extract, the following results were obtained: 0.24% protein, 2.31% sugar, 0.09% ash, 1.41% lipid, 0.91% titratable acidity, 42.88 mg of Galic acid eq. / g extract (phenolic), pH of 5.30, 90.93% moisture and 1.81 ng aflatoxin / mL extract (aflatoxin). In the analysis of the powders, moisture was lower for powders dried at 170ºC and with 10% maltodextrin concentration and was always lower than the control. The hygroscopicity is lower as higher the concentration of maltodextrin, since the last has low hygroscopicity. Higher temperatures generated more hygroscopic powders, because they reduced moisture. In concern to solubility, the values ranged from 85.60 to 91.91%; higher values were obtained for powders with higher concentrations of maltodextrin, since it has high solubility values. The control showed lower solubility of 77.62%. The color parameters were influenced only by the concentration of maltodextrin; the samples with lower concentrations showed more pronounced color, what was to be expected since maltodextrin is white. Therefore, controls have always presented with more intense color than the atomized powders. The temperature of 170 ºC originated powders with smoother surfaces, thus resulting in better flow. In the evaluation of stability, it was found that the atomized sample suffered lower color loss compared to the freeze dried sample, and samples with higher concentrations of maltodextrin (30%) had better preservation of total phenolics, especially at a temperature of 150ºC. In concern to antioxidant activity, the T5 treatment stood out compared to the others, showing the best values of antioxidant activity in all methods studied. The extract of peanut skin in powder also showed antimicrobial activity against Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes, with bactericidal properties against Staphylococcus aureus. This study clearly showed that peanut skin is a potential natural additive product and may be used as a powdered pigment which has excellent stability, low hygroscopicity and high solubility, besides having biological activities, such as antioxidant and antimicrobial capabilities.
Souza, João Francisco Ventrici de. "Efeito de materiais particulados em sistemas modelos de biomembranas." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-13042012-144908/.
Full textThis work presents some of the properties of mimetic systems of pulmonary surfactants (PS) composed of dipalmitoylphosphatidylcholine (DPPC) and DPPC/cholesterol and their interactions with particulate material (PM) originated from the burning of sugar cane leaves which is known by clinical studies as an injurious agent of the respiratory airways. The PM described in the present work was analyzed by different techniques: Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM) with EDS (Energy Dispersive Spectrometry) and Fourier Transformed Infrared Spectroscopy (FTIR). The average values of size and zeta potential were 250 nm and -27 mV, respectively. DPPC and DPPC/cholesterol -A isotherms were studied in the absence and presence of particles and it brought some information about the particle insertion in the monolayers. The DPPC/cholesterol system showed smaller changes in the minimum area per molecule with the increase of PM concentration which indicates the cholesterol acts as an organizer in the monolayer. Dilatational surface rheology data indicated that smaller PM concentrations increase the fluidity of the monolayers while the higher PM concentrations increase their rigidity. Cholesterol enhances the effects provoked by PM. Compressional modulus data obtained from the isotherms showed to be very close to those obtained from the rheological studies performed at higher frequencies. The transferred monolayers, using Langmuir-Blodgett technique, to solid supports were analyzed by Atomic Force Microscopy (AFM) and Fluorescence Lifetime Imaging Microscopy (FLIM) which showed that the particles are deposited together with the film and the DPPC/cholesterol system presents a more homogeneous particle arrangement. FLIM images showed that most likely this arrangement is due to the preference of cholesterol to allocate in regions surround the particles, granting stability to them in the monolayers. The study allowed concluding that PM originate from burned sugar cane leaves has an effect over some features of PS model systems and those properties have the potential to interfere in the perfect performance of these systems in biological environments.
Růžička, Tomáš. "Tržní příležitosti pro moderní perorální antibiabetika a position nového přípravku." Master's thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-77780.
Full textZhang, Ting. "Studies of DPPA & LPS Monolayers on Aqueous Solutions by Surface Tensiometry and Brewster Angle Microscopy." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417622850.
Full textTai, Zhongtian. "Aircraft electrical power system diagnostics, prognostics and health management." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/9593.
Full textShen, Jie. "The role of Decapentaplegic (Dpp) in Drosophila wing development." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1102321765343-79763.
Full textBuchholz, Alexander Karl. "DPP: Dual Path PKI for Secure Aircraft Data Communication." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/20373.
Full textThis thesis presents a solution to handling many of the potential security issues in aircraft data communication. This is accomplished through the implementation of a Dual Path PKI (DPP) design which includes a novel approach to handling certificate revocation through session certificates. DPP defines two authentication protocols, one between aircraft and another between aircraft and ATC, to achieve source authentication. Digital signature technology is utilized to achieve message content and source integrity as well as enable bootstrapping DPP into current ATC systems. DPP employs cutting-edge elliptic curve cryptography (ECC) algorithms to increase performance and reduce overhead.
It is found that the DPP design successfully mitigates several of the cyber security concerns in aircraft and ATC data communications. An implementation of the design shows that anticipated ATC systems can accommodate the additional processing power and bandwidth required by DPP to successfully achieve system integrity and security.
Master of Science
Oliveira, Sandro de. "Determinação da capacidade antirradicalar de produtos naturais utilizando-se a quimiluminescência do luminol e ensaios fotométricos com radicais estáveis." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-05122011-114158/.
Full textLiving organisms are exposed to the oxidative action of reactive oxygen species (ROS), causing a series of degenerative diseases such as cancer, atherosclerosis, diabetes, arthritis and heart disease. Studies have shown that consumption of antioxidant substances in the daily diet can prevent these oxidative processes that cause premature aging of the organism. Much attention has been paid in the last decades on the discovery of new natural antioxidants for its use in food or pharmaceutical industry, with the aim of replace synthetic antioxidants, which have restrictions due to their toxic potential. In this study, we compared the results from antiradical capacity determinations of several phenolic derivatives including natural products obtained by two different assays. One of them utilizes the stable radical DPPH• and the other the radical cation ABTS•+ as reagents and both have the advantage of a simple analytical method and ease in data collection as well as high data reproducibility. Furthermore, we have developed a method with DPPH• for the evaluation of the antirradicalar capacity of phenolic compounds in acid and buffered hydroalcoholic media, in order to facilitate the determination of the antiradical capacity of flavonoids and similar compounds in aqueous ambient and to allow differentiation between the capacity of different ionization states of these derivatives. Finally the chemiluminescent luminol/hemin/H2O2 assay, developed by our research group, has been utilized for the determination of the antiradical capacity of extracts, phases and fractions of Baccharis regnelli and the new parameter \"Trolox Percentage\" is being proposed to adequately express the antiradical capacity of complex mixtures. The sensibility of the luminol assay has been found to be higher than that of other methods and is shown to be suitable for the determination of antiradical activity parameters of complex natural product mixtures, contributing to the isolation of new substances with antiradical activity.
HAMAJIMA, NOBUYUKI, KENJI WAKAI, GUANG YIN, RIEKO OKADA, SAYO KAWAI, EMI MORITA, ERINA KOYAMA, et al. "DPP4 Genetic Variants Influence Baseline Prostate-Specific Antigen Levels: The J-MICC Study." Nagoya University School of Medicine, 2013. http://hdl.handle.net/2237/17603.
Full textJanovik, Vanessa. "AVALIAÇÃO QUÍMICA E ATIVIDADE ANTIOXIDANTE DAS CASCAS E TRITERPENÓIDES OBTIDOS DE CARINIANA DOMESTICA (MART) MIERS." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/6040.
Full textThe Lecythidaceae family consists of about 230 species, classified in some 10 genera. The species Cariniana domestica (Mart) Miers is one of several Jequitibá species, the oldest and millenary trees from Brazil. The present work developed studies with the aim of characterize the species when concerning to chemical aspects, in order to contribute to the knowledge improvement about Lecythidadeae family. The barks of C. domestica were collected in Tangará da Serra-MS. Exsiccate was archived as voucher specimen in the herbarium of Department of Biology at UFSM (SMDB 11818). Plant material was dried, crushed and powdered. The powder was submitted to hidroalcoolic maceration (7:3, v/v) and concentrated under reduced pressure. The remained aqueous extract was partitioned to obtain the fractions FCH2Cl2, F-AcOEt e F-BuOH. Chromatographic procedures led to the isolation of phytosterols (β-sitosterol + stigmasterol) and pentacyclic triterpenes (lupeol + β- amyrin), which were identified by means of spectroscopic (1H-NMR and 13C-NMR) and chromatographic (GC/MS and HPLC) methods. Additionally, the antioxidant capacity was evaluated by measuring its scavenging ability on DPPH and also using TBARS assay. Contents of total polyphenolic and flavonoid were measured as well as a chromatographic profile searching for phenolic substances was determined.. From F-CH2Cl2, DPPH assay revealed high scavenging ability with IC50 values that ranged from 6.5 ± 0.81 to 19.5 ± 1.32 μg/mL. IC50 values obtained with TBARS assay ranged from 11.11 ± 0.85 to 44.5 ± 2.31 μg/mL. Polyphenolic contents varied from 54.6 ± 0.33 to 309.3 ± 2.73 mg/g. Total flavonoid and condensed tannin contents varied from 12.0 ± 0.12 to 14.18 ± 0.1 and 131 ± 0.03 to 149.7 ± 0.22, respectively. HPLC analysis revealed the presence of gallic, caffeic and chlorogenic acids, as well as the flavonoids rutin, quercetin and kaempferol. The carotenoids lycopene and β- carotene were identified in dichloromethane fraction. The results revealed that the species C. domestica achieves antioxidant properties and the compounds identified for the first time for this species can be related to its popular uses.
A família Lecythidaceae consiste em cerca de 230 espécies, classificada em 10 gêneros. A espécie Cariniana domestica (Mart) Miers é uma das diversas espécies de Jequitibá, as árvores milenares mais antigas do Brasil. O presente estudo teve o objetivo de caracterizar quimicamente a espécie, visando contribuir para um maior conhecimento sobre a família Lecythidaceae. As cascas de C. domestica foram coletadas no município de Tangará da Serra-MS e o material foi catalogado sob o registro SMDB 11818 no departamento de Biologia da UFSM. O material vegetal foi seco, triturado e moído. O pó obtido foi submetido à maceração hidroalcóolica (7:3, v/v), seguindo-se de concentração em evaporador rotatório. A partição do extrato aquoso remanescente originou as frações F-CH2Cl2, F-AcOEt e F-BuOH. Os procedimentos cromatográficos de isolamento levaram à obtenção do fitoesteróis (β-sitosterol + estigmasterol) e triterpenos pentacíclicos (lupeol + β-amirina), os quais foram identificados por métodos espectroscópicos (1H-RMN e 13C-RMN) e cromatográficos (CG/EM e CLAE). Adicionalmente, foi avaliada a capacidade antioxidante frente ao radical DPPH, bem como utilizando o método do TBARS. Foram ainda realizadas dosagens investigativas quanto ao teor de polifenóis totais e flavonóides e um perfil cromatográfico para identificação de alguns compostos fenólicos também foi traçado. Os ensaios com o radical DPPH revelaram elevada capacidade seqüestradora de radicais livres, sendo que os valores de IC50 obtidos variaram de 6,5 ± 0,81 a 19,5 ± 1,32 μg/mL. No ensaio do TBARS, os valores de IC50 obtidos variaram de 11,11 ± 0,85 a 44,5 ± 2,31. A determinação de polifenóis totais revelou um teor variável de 54,6 ± 0,33 a 309,3 ± 2,73 mg/g. As determinações de flavonóides totais e taninos condensados variaram de 12,0 ± 0,12 a 14,18 ± 0,1 mg/g e 131 ± 0,03 a 149,7 ± 0,22, respectivamente. A análise por CLAE revelou a presença dos ácidos gálico, caféico e clorogênico, além dos flavonóides rutina, quercetina e campferol. Na fração diclorometano foram identificados os carotenóides licopeno e β-caroteno. Os resultados obtidos demonstram que a espécie C. domestica apresenta propriedades antioxidantes e os compostos identificados pela primeira vez para esta espécie podem estar relacionados com seus usos populares.
Raudonis, Raimondas. "Efektyviosios skysčių chromatografijos - pokolonėlinės reakcijos metodo vystymas antioksidantinio aktyvumo nustatymui." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080616_100532-09677.
Full textThe most important attention is paid to the search of natural antioxidants and their evaluation in medicinal and food raw materials of plant origin. A number of plants, their extacts, food products and medicinal preparations appear to be objects of scientific research. Effectiveness and informative character of research, undoubtedly, depend on relevance, sensitivity and efficiency of the methods chosen. Aim of this work is development and validation of post column HPLC-DPPH method as well as its application in antioxidant activity evaluation of known and unknown compounds fixing free radicals and existing in medicinal plant raw materials. HPLC separated compounds are identified at wave length of 275 nm and then the mobile phase with analytes flows by mixing tee to the reaction coil, where DPPH reagent solution is supplied. The solution flow rate – 0,4 ml/min. The reaction coil is connected with UV/Vis type detector, which measures absorption of flowing solution at wave length of 520 nm. It was dermined that vitexin rhamnoside, the dominant compound in the leaves of Crataegus monogyna, is not significant radical sacavenger. The most active antioxidant in leaves and the flowers of C. monogyna is chlorogenic acid. The most active antioxidant in Origanum vulgare raw materials is rosmarinic acid. Identified analytes in the extracts of Achillea millefolium that possessed radical scavenging properties were chlorogenic acid, luteolin-7-O-glucoside, rutin and luteolin.
Dalgê, Jéssica Jamila. "Estudo da capacidade antioxidante, antimicrobiana e anti-hemolítica do gengibre (Zingiber offinale)." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/74/74132/tde-08092015-083147/.
Full textThe aim of this study was to determinate antioxidant capacity, antimicrobial activity and anti hemolytic action of ginger (Zingiber officinale) extract obtained by different solvents. For this purpose, dried ginger flakes were powdered and used in ratio 1:50 (w/v) in the four different extractions: water, ethanol (70%), acetone/acetic acid (70%/2%) and acetone (70%). The extract was centrifuged and used for phenolic compounds determination by Folin-Ciocalteau and action on ABTS+. and DPPH. radicals. The best extractor solvent was selected by its antioxidant properties and easier elimination from the matrix. The select extract was submitted on evaporation and lyophilization, and subsequent re-suspension on phosphate buffer saline (PBS). Then, this suspension was used in biologic studies as NO scavenging, antioxidant action on induced hemolysis and effect on S. aureus growth. The values were express as mean and standard deviation. Statistical analysis carried out by Minitab® using ANOVA and Tukey to p< 0.05. Acetone ginger extract showed highest value of phenolic content (8.52 ± 1.24 mg galic acid equivalent /g of ginger). The acetone extract showed the lowest EC50 value and higher antioxidant action on ABTS+., 0.07 ± 0.01 mg of dry weight of the extract/mL of assay and 10.93 ± 0.79 mg trolox equivalents (TE)/g of ginger, respectively. These values did not show significant difference in relation to ethanol and acetone/acid extracts. For DPPH. assay, acetone extract showed lower value of EC50 (0.15 ± 0.01 mg dry weight of extract/mL assay) and higher antioxidant action (8.35 ± 0.60 mg TE/g of ginger), without significant difference in relation to ethanolic extract. Among all extracts, aqueous extract showed lesser satisfactory results. Acetone extract was selected for biological assays. Ginger extract (17.25 mg of dry weigth/mL) inhibited 50% of products formation on NO scavenging assay, similarly to galic acid results. Lower extract concentrations as 1.25 mg/mL inhibited 33% of NO. The 100% of hemolysis prevention was obtained by concentrations of ginger extract higher than 113 µg of dry weight of extract/mL of assay. Similar result was observed by presence of ascorbic acid. Erythrocytes lysis was avoided in 44% by 57 µg/mL of ginger extract. Ginger extract did not show antimicrobial action on S. aureus. In conclusion, ginger extract, in present conditions, showed antioxidant action on ABTS+. and DPPH. assays and in biological model systems as in NO scavenging assay and cell membrane lysis.
Korkmaz, Filiz. "Biophysical Studies Of Progesterone-model Membrane Interactions." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1116060/index.pdf.
Full textCalhoun, Robert Lee. "Electrochemisty and electrogenerated chemiluminescence of Ru(phen)₂dppz(BF₄)₂ both free and intercalated into DNA." Thesis, 2007. http://hdl.handle.net/2152/3006.
Full textTang, Hung-Kuan, and 唐弘寬. "Biochemical Characterization of Dipeptidyl Peptidase IV (DPP-IV) and DPP9." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/81400866916411761559.
Full text國立中央大學
化學工程與材料工程研究所
97
The family of prolyl dipeptidases has attracted extensive investigation in recent years because of their unique ability to cleave the peptide bond after a penultimate proline residue. It includes dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5), FAP (fibroblast activation protein), DPP2 (E.C. 3.4.14.2), DPP8 and DPP9. DPP-IV is the most extensively studied, and the functions for other members are not known so far. DPP9 and DPP8 are highly homologous proteases with 58% sequence identity at the amino acid level. Both the structure and function of these two proteases are not known. In this thesis, we first characterized the biochemical property of DPP9 including its enzymatic activity, quaternary structure, substrate specificity and pH optimum. DPP9 was expressed and purified from the baculovirus-infected insect cells using Strep•TactinTM purification system. The yield is significantly higher than what was reported in the literature. DPP9 has similar enzymatic activity, substrate specificity and pH optimum as DPP8. Both of them are homodimeric. Single site mutation at the C-terminal loop (F842A), one of the dimer interfaces, results in dimeric DPP9 with little enzymatic activity. The results indicate that the interaction mode of dimerization is similar to that of DPP8, reported previously from our lab. Therefore, the biochemical property of DPP9 we discovered so far is almost identical to that of DPP8. We speculate that DPP9 and DPP8 carry out overlapping functions in vivo. We have also determined the expression profile of DPP9. DPP9 is ubiquitously expressed in different cell types including fibroblasts, epithelial and blood cells. Surprisingly, contrary to previous report, we found that the expression levels of DPP8 and DPP9 do not change upon the activation of T-cells such as PBMC and Jurkat cells. Because DPP8 and DPP9 are ubiquitously expressed, whether they involve in immunological function as speculated awaits further studies. The characterization of DPP9 reported here lays the foundation for revealing its function in the future DPP-IV is a validated drug target for human type II diabetes. DPP-IV inhibitors without DPP8/9 inhibitory activity have been sought because a possible association was reported between a “DPP8/9 inhibitor” and severe toxicity in animals. However, at present, it is not known whether the observed toxicity is associated with DPP8/9 inhibition, or an off-target effect induced by the compound. We investigated whether the inhibition of DPP8/9 is the cause of the severe toxicity in animals using a very potent and selective DPP8/9 inhibitor with different pharmacophore, 1G244. By Ki measurement, 1G244 is 15- and 8-fold more potent against DPP8 and DPP9, respectively, than the “DPP8/9 inhibitor”. Strikingly, the “DPP8/9 inhibitor” does not penetrate the plasma membrane but remains outside the cells, whereas 1G244 readily enters the cells, even at low doses. By repeatedly exposing Strague-Dawley rats to 1G244 by intravenous injection for a period of 14 days, we observed no significant toxicological symptoms associated with 1G244. Blood and serum chemistry parameters were all within the normal ranges for the treated animals. Because of the high potency, good membrane penetration and adequate tissue distribution of 1G244, the mild symptoms observed are probably associated with DPP8/9 inhibition. Our results demonstrate that there is no direct causal effect of DPP8/9 inhibition with toxicity in animals. Finally, we have examined the contribution of the propeller loop to the enzymatic activity and quaternary structure of DPP9 and DPP-IV. The propeller loop is one of the two dimer interfaces and its function for the structure and activity of prolyl dipeptidase family is not known. Because the crystal structure of DPP9 has not been resolved, we have identified the sequence corresponding to the propeller loop of DPP9 based on the sequence alignment with other members of prolyl dipeptidases, and computer modeling of DPP8 reported in the literature. The conserved residues or the corresponding residues whose mutations have drastic effects on DPP-IV structure and activity were chosen to be mutated. The mutant proteins were expressed and purified from insect cells. For DPP9, five mutations located on the propeller loop were generated, which include a complete deletion of the propeller loop (DEL), V319A, E325A, K328A and Y334A. Among them, the dimeric structure and enzymatic activity of V319A, E325A and K328A mutant proteins were similar to those of wild type DPP9. In contrast, Y334A and DEL fail to disrupt DPP9 dimers to monomers. However, the mutant dimers are inactive with kcat significantly decreased and Km increased. Interestingly, differential effects on the structure and activity of DPP-IV were discovered with mutations on the propeller loop. Based on the crystal structure of DPP-IV, we have identified two groups of residues on the propeller loop that are involved in inter-molecular and intra-molecular interactions, Y248 involved in intermolecular interaction, and Y238 and Y256 involved in intramolecular interaction. We have introduced single site mutation to these residues resulting in Y248F, Y248A, Y248T, Y238A and Y256A, respectively. We also generated a deletion mutation, called Del, by deleting the whole propeller loop. We demonstrated that phenyl group of Y248 is essential for dimer formation. Lack of phenyl group, such as Y248T, Y248A and Del, results in monomeric DPP-IVs with very low or no activities. Specifically, Y248A and deletion mutants result in monomers with no activity detectable, while monomeric Y248T has a low kcat and an unchanged Km. Difference on Km effects suggests that the hydroxyl group might be important for the integrity of the substrate binding pocket. Y238A and Y256A mutations result in a mixture of monomers and dimers. Intriguingly, the monomers of Y238A and Y256A were fully active as the dimers. This is drastically different from all the monomeric mutations we generated previously. Further work will be required to fully understand the underlying mechanism of these active monomeric DPP-IVs. In summary, our results demonstrate that the propeller loop exerts differential effect on the structure and activity of DPP-IV and DPP9. Understanding how propeller loop affects the structure and activity of prolyl dipeptidases will help the understanding of the biogenesis and folding of homomeric proteins in the future.
NHANG, YONG-JI, and 張永佶. "含磷雙牙配子VIB金屬羰基錯合物,Cr(CO)��(dppm)、M��(CO)��(dpph)(M=Cr,Mo)、Mo��(CO)��(dppo)和Cr(CO)��(BDPH)之合成及結構研究." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/45813905265453833384.
Full textKilfoil, Maria. "p2sH NMR studies of the effect of the DPPC/DPPG ratio on bilayer properties in the presence of Cap2sp+s /." 1997.
Find full textLI, JIA-QING, and 李家慶. "含磷雙牙團配子VIB金屬羰基配位錯合物-W(CO)��(BDPH),W��(CO)��-(u-dpph),MO��(CO)��(μ-dppd)及W��(CO)��(μ-dppd)的結構研究." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/90433723381023872398.
Full textKu, Hui-Chun, and 辜惠君. "The cardioprotective effects of DPP4 deficiency." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/52006893107154725210.
Full text國立臺灣大學
藥理學研究所
100
Dipeptidyl peptidase-4 (DPP4) enzyme inhibition has been reported to increase plasma glucagon-like peptide-1 (GLP-1) level for controlling postprandial glucose concentration. Both DPP4 inhibitors and GLP-1 analogue have been approved as antihyperglycemic agents in the treatment of diabetes. In addition to the insulinotropic effect, GLP-1 signaling was discovered for the improvement of cardiovascular disease. We examined whether genetic mutation of DPP4 influence cardiac response in both animal model experiments and cell studies. Adult Fischer 344 (wild type) and DchcHsd-DPP IV (served as DPP4 deficiency) rats were used. DPP4 activity of DPP4-deficient rats is about one third of that in wild-type rats. Animal model experiments of endotoxemia and myocardial infarction were performed and compared in two kinds of rats. Cardiac function was assessed by pressure-volume loop monitoring. In some studies, GLP-1 analogue (exendin-4) or receptor antagonist (exendin-(9-39)) were used to identify the signaling of the protective effect. The blood plasma samples were collected and the hearts were harvested at the end of the experimental model. Adult cardiomyocyte was also isolated in two kinds of rats, and the effects of H2O2 induced ROS stress were compared. Cell viability, ROS staining, and proapoptotic signaling were executed to determine the response to H2O2. Endotoxemia was induced by the administration of lipopolysaccharide (LPS, 10 mg/kg, i.v.), and all the experiments were performed after 4 h of treatment. LPS-induced suppression of cardiovascular function in wild-type rats was associated with a significant reduction in cardiac cAMP level, phosphorylation of phospholamban, and attenuation of aortic contractile response to phenylephrine. DPP4-deficient rats had better preservation of cardiovascular function than wild-type rats during endotoxemia, which was correlated with a more prominent elevation of GLP-1 signaling. These findings coincided with the pretreatment of GLP-1 analogue, exendin-4, where the deterioration of cardiovascular function during endotoxemia was significantly reversed in wild-type rats. Furthermore, the benefit of DPP4 deficiency or GLP-1 analogue not only preserved cardiovascular function but also alleviated multiple organ injury and improved survival rate during endotoxemia. In brief, this study demonstrated that the resistance to LPS in DPP4-deficient rats seems to be derived from the higher GLP-1 production, while exendin-4 exerts protective effect in endotoxemia. For the myocardial infarction experimental models, rats were subjected to 45 min of coronary artery occlusion, and followed by reperfusion for 2 h. As compared to wild-type rats, after ischemia/reperfusion (I/R), DPP4-deficient rats had better cardiac performance in association with less infarct size and cardiac injury markers (LDH, ANP, and BNP), which could be attenuated by exendin-(9–39), a GLP-1 receptor antagonist. Exendin-(9–39) could diminish the increased phosphorylation levels of myocardial AKT and GSK-3β as well as the higher expression of GLUT4 in post-infarcted DPP4-deficient rats. However, exendin-(9–39) could not completely abrogate the less infarct size in DPP4-deficient rats as compared with that in wild-type rats, implicating the involvement of GLP-1 receptor-independent pathway. Accordingly, this study demonstrated that the benefit of cardiac protective action against I/R injury in DPP4-deficient rats, which is mediated through both GLP-1 receptor-dependent and receptor-independent mechanisms. DPP4-deficient rats show resistance to endotoxemia and ischemia/reperfusion. However, the decrease of DPP4 activity simply augmented the GLP-1 signaling or that such decrease resulted in a functional change or induced new signaling pathways remain unclear. With above reasons, we compared two kinds of cardiomyocytes under oxidative stress induced by H2O2. Cardiomyocytes were isolated from two kinds of rats. The effect of H2O2-induced ROS stress was performed in the presence or absence of GLP-1. DPP4-deficient cardiomyocytes were found to be resistant to H2O2-induced cell death via diminishing ROS level, Bax/Bcl-2 ratio, and caspase-3 activity. GLP-1 was also shown to decrease H2O2-induced cell death in wild-type cardiomyocytes via increasing the phosphorylation of AKT, which was abolished by exendin-(9–39), suggesting the importance of GLP-1 receptor dependent pathway. However, GLP-1 did not further increase phosphorylation of AKT against H2O2-induced stress in DPP4-deficient cardiomyocyte, indicating a crucial role of GLP-1-independent mechanism in these events. These several studies suggest that higher GLP-1 concentration in DPP4 mutant rats may contribute to the resistance to LPS and myocardial infarction. The protective effect is associated with both GLP-1 receptor -dependent and -independent pathway. The receptor dependent pathway is via increasing phosphorylation of AKT to ameliorate cardiac injury. In addition to the blood glucose controlling effect, GLP-1 receptor agonist or DPP4 inhibitor may exert cardioprotective effect in diabetes, and possibly be used as a preventive or even as a novel therapeutic agent in septic shock and myocardial infarction.
Watts, Joel Christopher. "Characterization of Shadoo and DPPX: Two Proteins of Potential Relevance to Prion Biology." Thesis, 2008. http://hdl.handle.net/1807/11275.
Full text余信德. "Interfacial Properties of Mixed DPPC/Protein Monolayers." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/35140218342427995646.
Full text國立成功大學
化學工程研究所
85
The hysteresis behavior of air/protein solution interface with or without DPPC monolayer is studied. The air/protein solution interface shows reproducible hysteresis behavior, which implies that both γ-globulin and lysozyme molecules have good respreading ability, and also indicates the characteristics of the slow desorption and fast readsorption behavior of proteins. As tile DPPC monolayer is spread on the air/protein solution interface, the surface pressure jumps immediately and slowly decreases to reach an equilibrium value. The typical collapse behavior of DPPC monolayer is observed during the first compression-expansion cycle of the interface, but is less significant during the subsequent cycles. Due to the fast readsorption rate of protein and poor respreading ability of DPPC, the hysteresis behavior of air/protein solution interface with DPPC monolayer at 37℃ after three compression-expansion cycles is similar to that obtained for the air/protein solution interface without DPPC monolayer. However, at 25℃, the hysteresis behavior after three cycles still shows the characteristics of DPPC monolayer. Moreover, if the . DPPC monolayer is spread first and then the γ-globulin monolayer is spead, there is the collapse characteristics of DPPC monolayer during the first compression-expansion cycle, and die change of hysteresis area is smaller compared with that obtained by spreading γ-globulin monolayer before DPPC monolayer. However, the characteristics of DPPC monolayer is still more significant at 25℃ than at 37℃.
Chou, Tzung-Han, and 周宗翰. "Molecular Interactions of Mixed Monolayers Containing DPPC." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/70618641096228772150.
Full text國立成功大學
化學工程學系
87
This study investigated the behavior of mixed DPPC/cholesterol monolayers and mixed DPPC/DHDP monolayers at the air/liquid interface at 37 . For DPPC/cholesterol mixed system at the air/water interface, the measurements of surface pressure-area per molecule (P-A) isotherms and relaxation curves were carried out. In the thermodynamic analysis of the mixed monolayers, the areas of monolayers exhibited negative deviations from the ideal values at all compositions for lower surface pressures. However, at higher surface pressures, distinctively positive deviations from ideality were observed at lower DPPC contents. Excess free energies of mixing had been calculated and the most stable state of the mixed monolayer with xDPPC = 0.5 or 0.6 was found. Compressibilities of the mixed monolayers indicate that the addition of cholesterol increased the fluidity of a DPPC monolayer. Moreover, the relaxation kinetics of the mixed monolayers was investigated by measuring the surface area as a function of time at a constant surface pressure of 40 mN/m. It was shown that the relaxation processes could be described by the models considering nucleation and growth mechanisms. The mixed monolayer behavior of DPPC and DHDP on water and phosphate buffer subphases were investigated from the measurements of P-A isotherms. The P-A isotherms indicate that the two components were miscible in the condensed and collapse states at the interface. The miscibility and nonideality of the mixed monolayers were examined by calculating the excess area as a function of composition, and deviations from ideality were observed, which suggests that the existence of attractive interactions between DPPC and DHDP molecules in the mixed monolayers on both subphases. Nevertheless, the presence of ions in the subphase may disturb molecular interactions and packing in the mixed monolayers, resulting in more expanded monolayers and complicated excess area behavior. Furthermore, the excess free energies of mixing and free energies of mixing were evaluated from the isotherms and the most stable state of the mixed monolayers on a water subphase was found with xDHDP = 0.5 or 0.6. However, it was shown that the mixed monolayers were more stable on a water subphase than on the phosphate buffer subphase.
Wang, Hong-Yu, and 王宏榆. "Microstructure of Mixed DPPC/PA Monolayer Observed by AFM." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/34984169513918620131.
Full text國立宜蘭大學
生物機電工程學系碩士班
104
The objective of this research is to study the stability of DPPC/PA monolayers at air-water interface. DPPC and PA are the main compositions of human pulmonary surfactants that contribute to the surface tension-lowering ability of pulmonary surfactants. Previous studies indicated that DPPC alone cannot substitute natural pulmonary surfactant to restore the normal function of a lung because the DPPC monolayer is unstable over its dynamic compression–expansion cycle. A LB film balance system was utilized to monitor the dynamic surface pressure-area isotherms. We also used an atomic force microscope to explore the microstructure of mixed DPPC/PA monolayers which was transferred to mica substrate by LB film technique. The five different mixed ratio of DPPC/PA is 1/9, 3/7, 5/5, 7/3, and 9/1. The results indicate that the collapse structure of DPPC is a convex granule-like structure accompanied with concave disk-like metastable structures, and the collapse structure of PA formed irregular convex structure. At surface pressure 45 mN/m, many cavities with depth of about 1 nm are observed for DPPC monolayer. We propose that these cavities will aggregate to form the disk-like metastable structures for increasing surface pressure. In mixed 9/1 DPPC/PA monolayer, the cavities appear at surface pressure 20 mN/m. However, the surface pressure of the cavities appear increases with increasing PA ratio.
Chen, Yan-shi, and 陳衍錫. "The effect of sterol on the POPE/DPPC membranes." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/3dytbq.
Full text國立中央大學
生物物理研究所
101
The specialized membrane microdomain was found in the mammalian cells membrane which termed lipid rafts with different physical and chemical properties. The lipid rafts contain 3 to 5-fold the amount of cholesterol found in the surrounding bilayer. Like cholesterol in mammalian cell membrane, ergosterol is important to the raft in the yeast cell membrane. To gain a better understanding of the effect of sterols on biological membrane properties requires investigations of the phase behavior. We study the physical properties of model membranes for binary mixture containing DPPC and POPE, and ternary mixtures containing DPPC, POPE and ergosterol using fluorescence microscopy and deuterium nuclear magnetic resonance (2H-NMR). The morphology of model membranes was observed as a function of temperature and composition by fluorescence microscopy. DPPC or POPE was deuterium labeled alternatively such that the phase behavior of both DPPC and POPE can be observed by 2H-NMR. 70:30 POPE/DPPC are in coexistence of 2 types of so phases at 15 ℃. As the DPPC concentration increases to 50 mol%, the POPE-rich so phase disappears and lipid bilayer only showed DPPC-rich so phase. The results of ternary mixtures containing sterol are compared with those of binary mixture to investigate the effect of sterol. In the 70:30 DPPC/POPE and 50:50 DPPC/POPE, ergosterol induces the formation of a lo phase in the so-phase bilayers. Finally, we present a partial phase diagram to summarize our findings.