Teses / dissertações sobre o tema "Molecular selectivity"
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Rajbanshi, Arbin. "Supramolecular interactions from small-molecule selectivity to molecular capsules". Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3879.
Texto completo da fonteBouanga, Boudiombo Jacky Sorrel. "Molecular selectivity by host-guest methods". Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33667.
Texto completo da fonteFransson, Linda. "Molecular modelling - understanding and prediction of enzyme selectivity". Licentiate thesis, KTH, School of Biotechnology (BIO), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10532.
Texto completo da fonteMolecular modelling strategies for evaluation of enzyme selectivity wereinvestigated with a focus on principles of how molecular interactionscould be evaluated to provide information about selectivity. Althoughmolecular modelling provides tools for evaluation of geometrical andenergy features of molecular systems, no general strategies for evaluationof enzyme selectivity exist. Geometrical analyses can be based uponinspection and reasoning about molecular interactions, which provide aneasily accessible way to gain information, but suffer from the risk of biasput in by the modeller. They can also be based on geometrical features ofmolecular interactions such as bond lengths and hydrogen-bond formation.Energy analyses are appealing for their modeller independenceand for the possibility to predict not only stereopreference, but also itsmagnitude.In this thesis, four examples of enantio- or regioselective serinehydrolase-catalysed reaction systems are presented together with developedmodelling protocols for explanation, prediction or enhancement ofselectivity. Geometrical as well as energy-based methodology were used,and provided an understanding of the structural basis of enzymeselectivity. In total, the protocols were successful in making qualitative explanationsand predictions of stereoselectivity, although quantitative determinationswere not achieved.
Heung, Yen Ming Mary. "Molecular selectivity of phospholipase D in granulocyte function". Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241935.
Texto completo da fonteMaughfling, Edward John Rosewarne. "Molecular basis for the ligand selectivity of bombesin receptors". Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625098.
Texto completo da fonteBauer, Paul. "Computational modelling of enzyme selectivity". Doctoral thesis, Uppsala universitet, Struktur- och molekylärbiologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-326108.
Texto completo da fonteErlenbach, Isolde. "The molecular basis of V2 vasopressin receptor-G protein coupling selectivity". [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963474448.
Texto completo da fonteKröger, Wendy Lee. "A molecular basis for the C-domain selectivity of angiotensin-converting enzyme". Doctoral thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/3134.
Texto completo da fonteKroger, W. "A Molecular Basis for the C-Domain Selectivity of Angiotensin-Converting Enzyme". Doctoral thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/3135.
Texto completo da fonteBlgacim, Nuria. "Molecular Control of the δ-opioid Receptor Signaling and Functional Selectivity by Sodium". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37806.
Texto completo da fonteBlockley, Alix Dawn. "Investigating the molecular basis of resistance and pyrethroid selectivity at acarine sodium channels". Thesis, Birkbeck (University of London), 2017. http://bbktheses.da.ulcc.ac.uk/252/.
Texto completo da fonteHermit, Mette Brunsgaard. "Molecular pharmacology of metabotropic glutamate receptors : focus on group III and subtype selectivity /". [Kbh.] : Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, 2004. http://www.dfh.dk/phd/defences/mettehermit.htm.
Texto completo da fonteLee, Kyoungmi. "DEVELOPMENT OF PROTEIN-IMPRINTED POLYSILOXANE BIOMATERIALS: PROTEIN SELECTIVITY AND CELLULAR RESPONSES". Lexington, Ky. : [University of Kentucky Libraries], 2005. http://lib.uky.edu/ETD/ukybien2005t00373/Thesis.pdf.
Texto completo da fonteTitle from document title page (viewed on January 19, 2006). Document formatted into pages; contains: viii, 59 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 53-58).
Zaidi, Saheem. "Understanding ligand binding, selectivity and functions on the G protein-coupled receptors: A molecular modeling approach". VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/596.
Texto completo da fonteGoldberger, Natalie Elizabeth. "A comprehensive investigation into the molecular mechanism responsible for selective androgen receptor (SARM) tissue-selectivity". Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1202342545.
Texto completo da fonteLivesey, Matthew Robert. "Molecular determinants of single channel conductance and ion selectivity in cationic Cys-loop receptor channels". Thesis, University of Dundee, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510623.
Texto completo da fonteFacey, Glenn Angus Carleton University Dissertation Chemistry. "Solid state NMR studies of the chiral selectivity, molecular motion and reactivity of guest molecules in tri-o-thymotide clathrates". Ottawa, 1991.
Encontre o texto completo da fonteMalmberg, Michelle. "Probing the G protein selectivity of FR900359 by means of molecular modeling and site directed mutagenesis". Thesis, Umeå universitet, Farmakologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-132256.
Texto completo da fonteAbrams, Christopher John. "Studies of the molecular basis of selectivity and gating in the inward rectifier potassium channel Kir2.1". Thesis, University of Leicester, 2000. http://hdl.handle.net/2381/29921.
Texto completo da fonteGiovanola, M. "MOLECULAR INSIGHTS IN ION ACCESS, DEPENDENCE AND SELECTIVITY IN THE NSS/SLC6 TRANSPORTERS KAAT1 AND GAT1". Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/232725.
Texto completo da fonteAlexander, Leila Tamara. "Mutational analysis of isoform selectivity and conformational equilibria in protein kinase inhibition". Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:6a2a12f6-4787-4398-81c0-fa5d6afe96f0.
Texto completo da fonteStankovic, Ivana 1986. "Dinâmica molecular de celulases : estudos de reconhecimento de substrato e propriedades conformacionais". [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248865.
Texto completo da fonteTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: A degradação enzimática da celulose proveniente de biomassa para a produção de bioetanol é realizada por um conjunto de proteínas denominadas celulases, as quais são produzidas por vários fungos e bactérias. O mecanismo molecular das interações físicas entre as celulases e a celulose é pouco conhecido. Para investigar estas interações, bem como as propriedades conformacionais e dinâmicas, nesta Tese usamos simulações por dinâmica molecular (MD). Abordamos duas celulases: a Endoglucanase 3 de Trichoderma harzianum (ThEG3) e a Endoglucanase de Xanthomas campestris pv. campestris (XccEG). O estudo dos mecanismos de reconhecimento de substrato por ThEG3 que falta o módulo de ligação à celulose (CBM), revela que a ausência de um CBM nesta estrutura é compensada pela presença de resíduos similares aos resíduos típicos de um CBM. O segundo estudo, sobre seletividade da XccEG, explica por que esta enzima catalisa a hidrólise somente de oligossacarídeos de cadeia igual ou maior que quatro unidades. Nossas simulações indicam que os quatro subsítios característicos da fenda de ligação ao substrato da XccEG precisam ser simultaneamente estabilizados pelas interações com substrato para promover uma ligação efetiva substrato-enzima. No terceiro estudo, investigamos as propriedades mecânicas do linker entre o domínio catalítico (CCD) e o CBM desta mesma enzima, composto por blocos de Thr e Pro, utilizando a técnica de replica exchange MD. Nossos resultados sugerem as bases moleculares da maior rigidez deste linker em comparação ao linker de celobiohidrolases II de Trichoderma reesei. Por fim, adaptamos o método de MDFF (flexible fitting MD) para gerar modelos de estrutura terciária a partir de dados de SAXS e o aplicamos para criar um modelo da estrutura intacta CCD-linker-CBM de XccEG
Abstract: The enzymatic degradation of the cellulose for the production of bioethanol is performed by a group of proteins called cellulases which are produced by various fungi and bacteria. The molecular mechanism of the physical interactions between the cellulases and a cellulose is little-known. In this work we use molecular dynamics simulations (MD) to investigate these interactions as well as conformational and dynamic properties. We have studied two cellulases: the endoglucanase 3 from Trichoderma harzianum (ThEG3) and the endoglucanase from Xanthomas campestris pv. campestris (XccEG). The study of the mechanisms of substrate recognition by ThEG3 which lacks the cellulose binding module (CBM) shows that the absence of a CBM in this structure is compensated by the presence of residues similar to typical CBM residues. The second study, on the selectivity of XccEG, explains why this enzyme catalyses only the hydrolysis of four or more units long oligosaccharides. Our simulations indicate that the four characteristic subsites of the substrate binding cleft of XccEG need to be simultaneously stabilized by the interactions with the substrate to provide an effective enzyme-substrate binding. In the third study, we investigated the mechanical properties of the linker between the catalytic domain (CCD) and CBM of the same enzyme, composed of Thr-Pro blocks, using the replica exchange molecular dynamics (REMD). Our results suggest the molecular basis of greater rigidity of this linker in comparison to the linker of cellobiohydrolase 2 from Trichoderma reesei. Finally, we have adapted the method of Molecular Dynamics Flexible Fitting (MDFF) to generate tertiary structure models from SAXS data and applied it to create a model of the intact structure CCD-linker-CBM of the XccEG
Doutorado
Físico-Química
Doutora em Ciências
Bakir, Ilyas. "Molecular studies of the γ-secretase complex activity and selectivity towards the two substrates APP and Notch". Thesis, Mälardalen University, School of Sustainable Development of Society and Technology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-9622.
Texto completo da fonteAlzheimer Disease (AD) is the most common neurodegenerative disorder in the world. One of the neuropathological hallmarks of AD is the senile plaques in the brain. The plaques are mainly composed of the amyloid β (Aβ) peptide. Aβ is generated from the amyloid precursor protein, APP, when it is first cleaved by the β-secretase and subsequently the γ-secretase complex. The γ-secretase complex cleaves at different sites, called γ and ε, where the γ-cleavage site generates Aβ peptides of different lengths and ε-cleavage generates the APP intracellular domain (AICD). The two major forms of Aβ is 40 and 42 amino acids long peptides, where the latter is more prone to aggregate and is the main component in senile plaques. The γ-secretase complex is composed of four proteins; Pen-2, Aph-1, nicastrin and presenilin (PS). The PS protein harbours the catalytic site of the complex, where two aspartate residues in position 257 and 385 (Presenilin 1 numbering) are situated. Most Familial AD (FAD) mutations in the PS gene cause a change in the γ-cleavage site, leading to a shift from producing Aβ40 to the longer more toxic variant Aβ42. Frequently, this often leads to impairments of the AICD production. Another substrate for the γ-secretase complex is Notch. It is important to maintain the Notch signaling since an intracellular domain (NICD) is formed after cleavage by the γ-secretase complex in the membrane (S3-site) and this domain is involved in transcription of genes important for cell fate decisions.
It has been reported that certain APP luminal juxtamembrane mutations could drastically alter Aβ secretion, however their effect on AICD production remains unknown. In this study we want to analyse wether the juxtamembrane region is important for the AICD production. To gain more insight into the luminal juxtamembrane function for γ-secretase-dependent proteolysis, we have made a juxtamembrane chimeric construct. A four-residue sequence preceding the transmembrane domain (TMD) of APP (GSNK), was replaced by its topological counterpart from the human Notch1 receptor (PPAQ). The resulting chimeric vector C99GVP-PPAQ and the wildtype counterpart were expressed in cells lacking PS1 and PS2 (BD8) together with PS1wt. We observed that the chimeric construct did not alter production of AICD when using a cell based luciferase reporter gene assay monitoring AICD production. We also introduced a PS1 variant lacking a big portion of the large hydrophilic loop, PS1∆exon10, since our group has previously observed that this region affect Aβ production143. We found that the absence of the large hydrophilic loop in PS1 gave a 2-fold decrease in AICD-GVP formation from C99GVPwt compared to PS1wt. The activity of PS1wt and PS1Δexon10 using C99GVP-PPAQ as a substrate gave similar result as the C99GVPwt substrate, i.e. a 2-fold decrease in AICD-GVP formation when comparing PS1Δexon10 with PS1wt. From this data we therefore suggest that the four residues in the juxtramembrane domain (JMD) (GSNK) is not altering ε-cleavage of APP when changed to Notch1 counterpart, PPAQ. Furthermore, we also show that the 2-fold decrease in AICD-production by the PS1Δexon10 molecule is not changed between the two substrates C99GVPwt and C99GVP-PPAQ. This indicates that the luminal region of APP is not directly involved in the ε-site processing. If the luminal region is affecting processing in the γ-cleavage sites, remains however to be investigated.
Cimenler, Ummuhan. "Molecular-Size Selective Zeolite Membrane Encapsulated Novel Catalysts for Enhanced Biomass to Liquid (BTL) Processes". Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6644.
Texto completo da fonteMedda, Federico. "Novel cambinol analogues as potential anticancer agents : an improved understanding of sirtuin isoform selectivity". Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1839.
Texto completo da fonteKetcha, Wanda Germain Jean Magloire. "Characterisation of oestrogenic properties of Isoflavones derived from Millettia griffoniana Baill.: - Molecular mode of action and tissue selectivity". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1154000965292-60098.
Texto completo da fonteNita, Sorin. "Insights into the solvation and selectivity of chiral stationary phases using molecular dynamics simulations and chemical force microscopy". Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1348.
Texto completo da fonteBrandt, Bjoern. "Selectivity in hydrocarbon conversions and methanol decomposition on a Pd/Fe 3 O 4 model catalyst". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15854.
Texto completo da fonteThe achievement of selectivity is one of the main objectives in chemistry. For catalysis, selectivity is generally seen to be closely linked with catalyst structure; the complex microscopic structure of real catalysts, however, obstructs to obtain a deeper understanding; for this reason, structurally simplified materials are studied. For the current work, studies have been conducted on a Pd/Fe3O4 model catayst. On this system, the selectivity in two catalytic reactions has been examined. The exposure of the reactants was effected by molecular beams in high vacuum, and the reaction rates have been measured mass spectrometrically; additionally, adsorbates were detected by IR-spectroscopy. - Decomposition of Methanol: It is shown that on the oxide Fe3O4 methanol is dehydrogenated very selectively to formaldehyde and water by reaction with surface oxygen of the oxide (Mars-van-Krevelen mechanism). On Pd metal it is mainly decomposed very quickly to carbon monoxide and hydrogen (and, in a side reaction, to carbonaceous deposits). Experiments are shown indicating that the diffusion of oxide-related methanol and methoxy to the Pd metal-particles contributes significantly to the overall activity of the model catalyst. - Conversion of 2-Butene with Deuterium: At first it is shown that the catalytic activity depends critically on the dissociative adsorption of the reactant deuterium, which is strongly inhibited by hydrocarbon adsorbates; it was, however, possible to overcome this limitation experimentally. In addition, it is shown that the hydrogenation reaction can be selectively induced in the presence of strongly dehydrogenated carbonaceous deposits, whereas the alternative reaction (H/D-exchange/isomerisation) can proceed also without the presence of those species; possible models for explanation are discussed. Finally, the possible origin of the different reaction rates with cis- and trans-2-butene that were observed only under certain reaction conditions is discussed.
Werner, Martin. "Low-Scaling Local and Fragment Self-Consistent Field Potentials in Molecular Systems". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://hdl.handle.net/11858/00-1735-0000-002E-E311-5.
Texto completo da fonteAyaz, Muhammad [Verfasser], Ralf [Akademischer Betreuer] Kaldenhoff e Gerhard [Akademischer Betreuer] Thiel. "Investigations on mercury sensitivity and molecular determinants of selectivity in two plant aquaporins. / Muhammad Ayaz. Betreuer: Ralf Kaldenhoff ; Gerhard Thiel". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2011. http://d-nb.info/1105564169/34.
Texto completo da fonteSun, Shangzheng. "Building up molecular complexity by Ni-catalyzed cross-coupling reactions". Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/670603.
Texto completo da fonteEn línea con la investigación desarrollada en nuestro grupo basada en la elaboración de reacciones de acoplamiento cruzado, hemos decidido centrar la tesis doctoral en el estudio de la formación de enlaces Csp3–Csp3, usando reacciones de acoplamiento cruzado reductoras catalizadas por níquel. En el primer capitulo, nuestros esfuerzos se centran en la preparación de una nueva metodología basada en la alquilación reductiva de a-haloboronatos usando como materia prima olefinas no activadas. Este protocolo, quimio- y regioselectivo, permite la incorporación de un fragmento alquílico-boronato en olefinas no activadas, y presenta unas condiciones de reacción suaves. Por otro lado, el uso de olefinas internas permite la formación de enlaces carbonocarbono en posiciones C-H sp3 lejanas, a través del proceso llamado “chain-walking”, catalizado por níquel. En el segundo capitulo, siguiendo nuestro interés en reacciones catalizadas por níquel, hemos estudiado un método catalítico de alquilación desaminativa de olefinas no activadas. Esta nueva metodología opera bajo condiciones de reacción suaves y se caracteriza por el amplio espectro de compuestos que pueden acoplarse selectivamente. Esta técnica también puede ser aplicada en el contexto de la derivatización del etileno y para la funcionalización de moléculas de alto valor añadido.
In line with our group research interests on cross-coupling-reactions, we decided to focus this doctoral studies on the development of sp3 C–C bond formation by means of nickel catalyzed reductive-cross-coupling. Our first effort was focused on the development of a reductive alkylation of a-haloboronates with unactivated olefin feedstocks. We have developed a mild, chemo- and site-selective catalytic protocol that allows the incorporation of an alkylboron fragment into unactivated olefins. Moreover, the use of internal olefins enables C C bond-formation at remote sp3 C-H sites via nickel catalyzed chain-walking process. Following up our interest on nickel catalyzed chainwalking events, we reported a site-selective catalytic deaminative alkylation of unactivated olefins. This method operates under mild conditions and is characterized by a wide substrate scope and exquisite site-selectivity profile. Particularly noteworthy is that this technique could be employed in the context of ethylene derivatization and for the late-stage functionalization of complex molecules. Our final efforts for the sp3 C–C bond formation was focused on the development of a regio-selective cross-coupling of three electrophiles by means of nickel/photoredox dual catalysis. We developed a modular, chemo- and regio-selective 1,2-difunctionalization of simple vinyl boronates with readily available organic halides.
Rungta, Meha. "Carbon molecular sieve dense film membranes for ethylene/ethane separations". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50121.
Texto completo da fonteGomes, Marcelo do Nascimento. "Planejamento, síntese guiada por QSAR, avaliação biológica e modelagem molecular de chalconas com atividade antituberculose". Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/7372.
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Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG
In view of the current panorama of tuberculosis (TB) pandemic in the world, aggravated by co-infection with the HIV virus and the emergence of resistant strains of Mycobacterium tuberculosis (M. tb.), The research and discovery of new Anti-TB drugs. The present work aimed at the planning, synthesis and biological evaluation of new compounds with anti-TB activity, candidates for TB drugs. Structure and activity relationship (SAR) studies were developed using Matched Pair Molecular Analysis (MMPA) and binary models of quantitative relations between structure and activity (QSAR) using a combination of molecular fingerprints and machine learning methods. Bioisosteric replacement were proposed to plan new aryl and heteroaryl chalcones using the information obtained from SAR and QSAR analyses. Thirty-three compounds were selected by the consensus QSAR model for the synthesis. These compounds were synthesized and their structures confirmed by infrared (IR), hydrogen nuclear magnetic resonance (1H NMR) and carbon (13C NMR) spectroscopic methods and mass spectrometry (MS). Compounds which showed high purity (≥95% in HPLC) were tested against strains of M. tb. H37Rv (sensitive) and resistant to rifampicin (RMP) or isoniazid (INH). In addition, they were also tested in mammalian cell cytotoxicity assays and activity spectrum. We identified 22 hits with anti-TB activity, with minimum inhibitory concentration (MIC) in M. tb. H37Rv in aerobic conditions (MABA) <10 μM. Of these, 12 compounds exhibited potent M. tb. replication activity on nanomolar scale, with MIC values in MABA <1 μM and in micromolar under anaerobic conditions (LORA) with MIC <10 μM. In addition, these compounds also showed potent inhibitory activity against monoresistant strains at RMP or INH (MIC <1 μM and MIC <10 μM, respectively). Hits also demonstrated low cytotoxicity in mammalian cells (Vero cells) and selectivity index between 11 and 545 for M. tb. The same selectivity was verified in the activity spectrum assay against four commensal strains and six strains of non-tuberculosis mycobacteria (NTMs), in which the compounds presented broad spectrum against the NTMs strains. These results demonstrated that the combination of in silico strategies for the design of aryl and heteroaryl chalcones was efficient in identifying new compounds that proved to be potent, selective and promising candidates for prototypes of anti-TB drugs.
Face ao panorama atual da pandemia de tuberculose (TB) no mundo, agravado pela co-infecção com o vírus HIV e o surgimento de cepas de Mycobacterium tuberculosis (M. tb.) resistentes aos fármacos utilizados, é urgente a pesquisa e descoberta de novos fármacos anti-TB. O presente trabalho objetivou o planejamento, a síntese e avaliação biológica de novos compostos com atividade anti-TB, candidatos a fármacos para TB. Foram desenvolvidos estudos de relação entre estrutura e atividade (SAR) utilizando o método Matched Pair Molecular Analysis (MMPA) e modelos binários de relações quantitativas entre estrutura e atividade (QSAR) utilizando combinação de descritores (fingerprints) moleculares e métodos de aprendizado de máquina. Substituições bioisostéricas foram propostas para planejar novas aril e heteroaril chalconas utilizando as informações obtidas nas análises de SAR e QSAR. Trinta e três compostos foram selecionados pelo modelo de QSAR por consenso para a síntese. Estes compostos foram sintetizados e suas estruturas foram confirmadas por métodos espectroscópicos no infravermelho (IV), de ressonância magnética nuclear de hidrogênio (RMN de 1H) e de carbono (RMN de 13C) e espectrometria de massas (EM). Os compostos que apresentaram elevado grau de pureza (≥95% em CLAE) foram testados contra cepas de M. tb. H37Rv (sensíveis) e resistentes a rifampicina (RMP) ou isoniazida (INH). Além disso, também foram testados em ensaios de citotoxicidade em células de mamíferos e espectro de atividade. Foram identificados 22 hits com atividade anti-TB, com concentração inibitória mínima (MIC) em M. tb. H37Rv em ensaios em condições aeróbias (MABA) <10 μM. Destes, 12 compostos exibiram potente atividade na replicação de M. tb em escala nanomolar, com valores de MIC em MABA <1 μM e em micromolar em condições anaeróbias (LORA) com MIC <10 μM. Ademais, esses compostos também apresentaram potente atividade inibitória contra cepas monoresitentes a RMP ou INH (MIC<1 μM e MIC<10 μM, respectivamente). Os hits também demonstraram baixa citotoxicidade em células de mamífero (células Vero) e índice de seletividade entre 11 e 545 para M. tb. A mesma seletividade foi verificada no ensaio de espectro de atividade frente a quatro cepas comensais e seis cepas de micobactérias não-tuberculose (NTMs), em que os compostos apresentaram amplo espectro contra as cepas NTMs. Estes resultados demonstraram que a combinação das estratégias in silico para o planejamento de aril e heteroaril chalconas foi eficiente na identificação de novos compostos que se mostraram potentes, seletivos e promissores candidatos a protótipos de fármacos anti-TB.
Hamnevik, Emil. "Characterization and Directed Evolution of an Alcohol Dehydrogenase : A Study Towards Understanding of Three Central Aspects of Substrate Selectivity". Doctoral thesis, Uppsala universitet, Biokemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-318984.
Texto completo da fonteHernández, Prat Anna 1984. "Antitumor effects of novel targeted therapies (TAK-228 and TAK-117) with high selectivity againts PI3K/AKT/mTOR pathway in bladder cancer : Defining molecular markers". Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/664507.
Texto completo da fonteAdvanced bladder cancer is associated with a poor prognosis and with limited treatment options. Despite of the recent success with the use of immune check-point inhibitors, not all patients will respond to therapy and there is still need for alternative options. PI3K/AKT/mTOR pathway is frequently activated in this pathology and can be a potential therapeutic target for treatment intervention. We studied the antitumor efficacy of TAK-228, an oral mTORC1/2 inhibitor in preclinical models of bladder cancer with signal transduction alterations of this pathway. We demonstrated strong inhibition of cell proliferation in vitro, and reduction of the tumor growth in vivo. Potential biomarkers of response are analysed. Strong synergistic effects were observed with the combination of TAK-228 and TAK-117 (PI3Kα inhibitor). TAK-228 did show improved efficacy when combined with paclitaxel. Further studies with TAK-228 will be needed to see if this preclinical therapeutic efficacy is translated into clinical benefit for selected bladder cancer patients.
Szczepaniak, Florence. "Efficient sampling of complex biomolecular assemblies using molecular simulations". Electronic Thesis or Diss., Université de Lorraine, 2024. http://www.theses.fr/2024LORR0115.
Texto completo da fonteAtomic-level information is essential to describe the structure and dynamics of biomolecular assemblies. The work presented in this thesis aims to explore and enhance computational techniques explaining the formation of complexes, quantifying binding free energies or describing the dynamics of multi-components systems. I first developed a protocol to compute the binding free energy of a ligand buried in a membrane protein. It relies on alchemical transformations carried out in a rigorous statistical mechanical framework. The protocol is distributed within the BFEE2 plugin, a tool designed to assist the end user in preparing all the necessary input files and performing the post-treatment of the simulations towards the final estimate of the binding affinity. Molecular Dynamics (MD) and alchemical simulations have been employed to provide insights into the formation of specific protein complexes in terms of structure and dynamics. The set of Dpr and DIP proteins, which play a key role in the neuromorphogenesis in the nervous system of Drosophila melanogaster, offer a rich paradigm to learn about protein-protein recognition. Many members of the DIP subfamily cross-react with several members of the Dpr family and vice-versa. While there exists a total of 231 possible Dpr-DIP heterodimer, only 57 “cognate” pairs have been detected by surface plasmon resonance (SPR) experiments, suggesting that the remaining 174 pairs have low or unreliable binding affinity. Here I assessed the performance of computational approaches to in quantifying the binding affinities between Dpr and DIP proteins and I identified by means of a series of point mutations, the interfacial residues governing the specificity of the recognition process. Building on alchemical transformations, I developed a hybrid nonequilibrium molecular dynamics - Monte Carlo (neMD/MC) simulation method aimed at enhancing the sampling of inhomogeneous membranes, circumventing the slow lateral diffusion of the various constituents. Randomly chosen lipid molecules are swapped to generate configurations that are subsequently accepted or rejected according to a Metropolis criterion based on the alchemical work associated to the attempted swap calculated via a short trajectory. The performance of the hybrid neMD/MC algorithm and its ability to sample the distribution of lipids near a transmembrane helix carrying a net charge are illustrated for a binary mixture of charged and zwitterionic lipids. To enforce equilibrium between a simulated system and an infinite surrounding bath, a modified version of the neMD/MC algorithm was developed, in which a randomly chosen lipid molecule in the simulated system is swapped with a lipid picked in a separate system standing as a thermodynamic “reservoir” with the desired mole fraction for all lipid components. Membrane proteins function has been shown to depend on the lipid organization within the membrane either through averaged bulk effect or specific binding. A well-known class of protein exhibiting such a dependance is the family of pentameric ligand-gated ion channels (pLGICs). Upon the binding of a neurostransmitter, the conformation of these proteins changes establing a ionic current at the synapse junctions, transforming therby a chemical into an electric signal. Here, we generated several MD trajectories of various agonist-bound structures of nicotonic acethlycholine receptors solved by cryoEM, providing a molecular basis shedding light on the desensitization process. The conductivity and the stability of the pore of the pLGICs in a desensitized state are measured. The functions of these proteins have also been shown to depend on lipid composition. Finally, we employed alchemical tranformations to quantify the relative binding affinities of anionic and zwitterionic lipids at putative pLGIC binding sites, enlightening how lipids modulate the fonction of these proteins
Zhang, Wei. "Directed Evolution of Glutathione Transferases with Altered Substrate Selectivity Profiles : A Laboratory Evolution Study Shedding Light on the Multidimensional Nature of Epistasis". Doctoral thesis, Uppsala universitet, Biokemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-158400.
Texto completo da fonteStallivieri, Aurélie. "Synthèse de systèmes à base de photosensibilisateurs pour l'amélioration de la sélectivité tumorale en thérapie photodynamique". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0128/document.
Texto completo da fonteOne limitation of photodynamic therapy is the low selectivity of photosensitizers (PS) to tumour tissue. The search of new PS more selective began to focus on the synthesis of PS coupled with substrate specific of the membrane receptors overexpressed in certain cancers. The acid folic receptor is overexpressed in ovarian carcinomas and PS were conjugated with folic acid. PS were also coupled with a specific peptide of neuropilin 1 overexpressed in tumoral cells of medulloblastoma. Another strategy for increasing the selectivity of the treatment is to produce reactive oxygen species specifically at the tumor site. The activity of enzymatic cleavage of biomarkers overexpressed in tumour areas is used. The gelatinases (MMP-2 and MMP-9) and their activator MMP-14 are known to play a key role in tumour angiogenesis and the growth of glioblastoma multiform. Different photodynamic molecular beacons (PMB), composed of a photosensitizer and a quencher linked together by a peptide substrate of gelatinases or MMP-14, were designed
Cisek, Katryna. "Rational Optimization of Small Molecules for Alzheimer’s Disease Premortem Diagnosis". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338325484.
Texto completo da fonteGonciaruk, Aleksandra. "Graphene and triptycene based porous materials for adsorption applications". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/graphene-and-triptycene-based-porous-materials-for-adsorption-applications(932755b9-1600-4f64-8683-00844645a58b).html.
Texto completo da fonteCabana, Jérôme. "Étude des déterminants structuraux de l'activation des voies de signalisation de la protéine G[indice inférieur q/11] et des β-arrestines par le récepteur de type 1 à l'angiotensine II". Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/7706.
Texto completo da fonteAbstract: Biased signaling represents the ability of G protein-coupled receptors to engage distinct pathways with various efficacies depending on the ligand used or on mutations in the receptor. Having better control over the signaling pathways activated or inhibited by drugs could lead to fewer undesirable effects. Unfortunately, the structural mechanisms involved in the transmission of signal across the cell membrane through the receptors are poorly understood, which limits the rational development of new molecules targetting specific signaling pathways. The angiotensin-II type 1 (AT[subscript 1]) receptor, a prototypical class A G protein-coupled receptor, can activate various effectors upon stimulation with the endogenous ligand angiotensin-II (AngII), including the G[subscript q/11] protein and β-arrestins. It is believed that the activation of those two pathways can be associated with distinct conformations of the AT[subscript 1] receptor. To verify this hypothesis, microseconds of molecular dynamics simulations were computed to explore interactions and movements that define the conformational landscape of the AT[subscript 1] receptor. We have also verified how this conformational landscape is modified by mutations (N111G, N111W, D74N) and ligands (AngII, [Sar[superscript 1]Ile[superscript 8]]AngII) that have different signaling properties on the G[subscript q/11] pathway and the β-arrestin pathway. The results provide a better understanding of the role of a hydrogen bond network formed of conserved polar residues in the receptor core which include residues N111[superscript 3.35] and D74[superscript 2.50]. The results also reveal the existence of a cluster of hydrophobic residues located right above the hydrogen bonds network and adjacent to the binding pocket that appears important for the stabilization of the ground state of the receptor as well as its ligand-induced activation. As a whole, the results suggest that activation of the G[supbscript q/11] pathway is associated with a specific conformational transition stabilized by the agonist, whereas the activation of the β-arrestin pathway is linked to the stabilization of the ground state of the receptor.
Patt, Antoine. "Simulation moléculaire d'hydrates de gaz mixtes en conditions astrophysiques". Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCK008.
Texto completo da fonteIn this PhD work, numerical simulation methods have been used in order to model clathrate hydrates at the molecular scale, in thermodynamic conditions typical of astrophysical contexts. The aim was to characterize the trapping abilities of those peculiar structures of water, by means of the tools used in adsorption studies. The results presented in the present thesis are focused on a couple of chemical species which are found to be abundant in our astrophysical vicinity and are quite similar: carbon monoxide, CO, and nitrogen, N2. Thus, the single-component clathrates of CO and N2, and the mixed hydrate CO-N2 have been studied, mainly using grand canonical Monte Carlo simulations. First, these clathrates have been examined as part of a bulk phase. A preferential encapsulation of CO molecules, with respect to N2 molecules, has been highlighted in the simulations, in agreement with recent experimental data and thermodynamic calculations. Secondly, the hydrate systems have been brought in contact with a gaseous interface in order to study the surface adsorption of CO and N2 molecules. Simulations with other forms of solid water, also found in astrophysical contexts, have been performed. All the considered surfaces have shown a greater molecular selectivity towards the trapping of CO molecules, compared to the one of hydrates' cages
Ferrari, Florent. "Étude de la sélectivité d'acylation enzymatique de peptides : prédiction de la sélectivité de la lipase B de Candida antarctica par modélisation moléculaire et recherche de nouvelles enzymes spécifiques de type aminoacylases". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0252/document.
Texto completo da fontePeptides exhibit various beneficial effects such as antioxidant, anti-hypertensive, neuroprotective, antiviral or antimicrobial activities. However, their use can be limited by their short half-life and their low biological availability. One solution to overcome these drawbacks is the acylation of peptides with fatty acids. This reaction called acylation can be catalyzed using enzymes. To date, very few studies focus on enzymatic acylation of peptides and on finding new enzymes catalyzing this reaction. The objectives of this work were, in a first time, to understand the selectivity mechanisms of the lipase B of Candida antarctica for peptides acylation combining experimental and molecular modeling approaches. This study highlighted enzyme/substrate interactions involved in the enzymatic selectivity and a modelexplaining the chemo- and regio-selectivity of this enzyme for peptide acylation reactions was built. In a second time, a preliminary study was carried out in order to identify new aminoacylase enzymes produced in the culture supernatant of various species of Streptomyces. These enzymes are able to catalyze acylation of peptides in aqueous media. A partial purification method was set and a comparative study was performed on the selectivity of C. antarctica lipase Band that of the new aminoacylases discovered in the culture supernatant of Streptomyces ambofaciens ATCC 23877. These enzymes presented a selectivity different from C. antarctica lipase B allowing the acylation of the N-terminal amino group of amino acids or peptides. A partial description of the aminoacylase activity of the supernatant crude extract of S. ambofaciens was performed. In a third and final part, a comparison of sequences of aminoacylases from Streptomyces mobaraensis with the genome of S.s ambofaciens ATCC 23877 was performed in order to identify genetic sequences encoding the new discovered aminoacylases from S. ambofaciens ATCC 23877. Each identified gene was deleted to correlate it with the aminoacylase activity observed in the crude extract of S. ambofaciens. Lastly, a heterologous expression of the ε-lysine acylase was initiated
Spencer, William John. "Phorbol ester-mediated NF-kappa-B transactivation is selectively inhibited by taxol". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0007/MQ44286.pdf.
Texto completo da fonteHijazi, Mohamad. "Capteur de gaz SnO2 fonctionnalisé fonctionnant à température ambiante, sensible et sélectif pour la détection d’ammoniac". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEM030/document.
Texto completo da fonteOne of the major challenges in the modern era is how we can detect the disease when we are still feeling healthy via noninvasive methods. Exhaled breath analysis is offering a simple and noninvasive tool for early diagnosis of diseases. Molecularly modified SnO2 sensors seem to be promising devices for sensing polar gases such as ammonia. SnO2 surface functionalization was performed in order to obtain sensitive and selective ammonia gas sensor that operates at room temperature. The first step of functionalization is the covalently attachment of 3-aminopropyltriethoxysilane (APTES) film on SnO2 in vapor or liquid phases. The characterization performed by the Infrared Spectroscopy and X-ray Photoelectron Spectroscopy, show that more APTES were grafted by hydrous liquid phase silanization. The second step was the functionalization of APTES modified SnO2 with molecules having acyl chloride of end functional groups molecules such as alkyl, acid and ester groups. Pure SnO2 and APTES modified SnO2 sensors did not show any significant sensitivity to ammonia (0.2-100 ppm) at 25 °C. On the contrary, acid and ester modified sensors are sensitive to ammonia between 0.2 and 10 ppm at room temperature. However, ester modified SnO2 was more selective than acid modified sensor regarding the ethanol and carbon monoxide gases. Ammonia variates the attached molecular layer’s dipole moment which leads to change in SnO2 conductance. Working at ambient temperature is also one of the advantages of these sensors in addition to the selectivity to ammonia regarding other gases such as ethanol, carbon monoxide and acetone
Dobrowolski, Curtis Noel. "HISTONE LYSINE METHYLTRANSFERASES SELECTIVELY RESTRICT HIV-1 IN CENTRAL MEMORY T-CELLS". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1522842870401743.
Texto completo da fonteElson-Schwab, Lev. "Selectivity in the interactions between positively charged small molecules and negatively charged biopolymers". Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3221498.
Texto completo da fonteTitle from first page of PDF file (viewed June 27, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
Pickup, Michael Brennan. "New methodology in the determination of sequence-selectivity in small molecule-DNA binding". Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286346.
Texto completo da fonteSun, Xixi. "Scaffolding Catalysis: Towards Regioselective Hydroformylation of Alkenes and Site-Selective Functionalization of Polyhydroxylated Molecules". Thesis, Boston College, 2013. http://hdl.handle.net/2345/3324.
Texto completo da fonteChapter 1. We reported the first synthesis of all-carbon quaternary centers via hydroformylations using a catalytic directing group. With the ability of reversibly and covalently binding to a substrate, and coordinating to a metal center, scaffolding catalyst 1.1 is able to direct the branch-selective hydroformylation of 1,1-disubstituted olefins under mild temperature. Chapter 2. We have designed and synthesized a chiral organocatalyst 2.11. This catalyst is able to covalently bind to one hydroxyl, and utilize the induced intramolecularity to stereoselectively functionalize the other hydroxyl within a cis-1,2-diol via electrophile transfer. Catalyst 2.11 was used in the desymmetrization of meso-1,2-diols under mild conditions (4 C to room temperature), leading to high yields and selectivities for a broad substrate scope. Chapter 3. Catalyst 3.1 and 3.6 were demonstrated to selectively bind to primary hydroxyls over secondary hydroxyls. By combining the binding selectivity with asymmetric catalysis, these scaffolding catalysts were shown to promote the selective silylation of secondary hydroxyls within terminal (S)-1,2-diols. The reversal of substrate bias was further applied to a regiodivergent kinetic resolution of racemic terminal 1,2-diols, producing secondary protected products in synthetically practical levels of enantioselectivity (>95:5 er) and yields (≥40%). Time course studies of this reaction further revealed the optimal condition to form the primary silylated product in high s-factor. Chapter 4. Based on the previous understanding of catalyst 4.5 and 4.6, the exclusive catalyst recognition of cis-1,2-diols within polyhydroxylated molecules was further discovered. This unique functional group display recognition was further allied with the catalyst's ability to stereoselectively differentiate hydroxyls within cis-1,2-diols, enabling the site-selective protection, functionalization, and activation of the inherently less reactive axial hydroxyl groups within carbohydrates. This methodology also enables the selective functionalization of multiple complex molecules, including digoxin, mupirocin, and ribonucleosides, demonstrating the potential power of scaffolding catalysis in the rapid access to valuable synthetic derivatives of polyhydroxylated compounds
Thesis (PhD) — Boston College, 2013
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Leeson, Philip. "Computer modelling of calixerene compounds capable of selectively extracting lanthanide metals from nuclear waste slurries". Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484312.
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