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Dissertations / Theses on the topic 'Protein-ligand complex'
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Qian, Yi. "Flipping a MAGUK switch : complex domain interactions regulating ligand binding to the tumor suppressor Dlg /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251819311&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 68-71). Also available for download via the World Wide Web; free to University of Oregon users.
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Fujishima, Sho-hei. "Development of Protein Labeling Methods for Functional Analyses in Biological Conditions." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157618.
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Spitzmüller, Andreas [Verfasser], and Gerhard [Akademischer Betreuer] Klebe. "Knowledge-based Optimization of Protein-Ligand-Complex Geometries / Andreas Spitzmüller. Betreuer: Gerhard Klebe." Marburg : Philipps-Universität Marburg, 2011. http://d-nb.info/1014851696/34.
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Holmes, Peter. "Structure and mode of action of the TolA-TolB complex from Pseudomonas aeruginosa." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:cccb0c88-5c89-4d21-81eb-70ebf513c7ab.
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Protein-protein interactions (PPIs) across the cell envelope of Gram-negative bacteria are critical for mediating signal transduction pathways that underpin cellular homeostasis. The Ton and Tol Pal systems are two conserved, ancestrally related protein networks that are also required for bacterial pathogenesis. Both Ton and Tol-Pal traverse the periplasm to effect different functions at the outer membrane (OM). Tol-Pal is composed of a homologous complex of three inner membrane proteins, TolQ-TolR-TolA (linked to proton motive force) and two additional periplasmic proteins TolB and Pal. The physiological role of the Tol-Pal system is to stabilise the OM, however the mechanism involved is unknown. TolA is however known to form a crucial protein-protein interaction via its C-terminus with the disordered N-terminus of TolB. Prior to this thesis, determination of the molecular features underlying a protein-protein complex between TolA and an endogenous binding partner TolB had never been accomplished. In this work, I describe the first structure comprising the TolA-TolB complex from Gram negative bacteria. The structure of this complex was determined from Pseudomonas aeruginosa by solution NMR spectroscopy. I determined the interaction between P. aeruginosa TolA and a TolB N terminal peptide to be relatively weak using fluorescence anisotropy. I found that TolB interacts with TolA through an analogous mechanism to that seen in TonB-dependent transporters. Based on these studies and bioinformatics analyses, I hypothesize that the evolutionary resilience of the Tol-Pal system to external pressures is contingent on the preservation of the TolA-TolB interface. Structure-based mutations within the TolA-TolB complex were also evaluated for their effect on in vivo function of the Tol-Pal complex and impact on complex formation in vitro. Taken together, the results demonstrate that protein networks which transduce energy to the OM through PMF-dependent systems in bacterial cells appear to follow a common β-strand augmentation mechanism.
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Sundqvist, Gustav. "Analysis of noncovalent and covalent protein-ligand complexes by electrospray ionisation mass spectrometry." Doctoral thesis, Stockholm : Bioteknologi, Biotechnology, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4728.
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Griswold, Ian James. "The structural role of CheW in the bacterial chemotaxis receptor complex /." view abstract or download file of text, 2001. http://wwwlib.umi.com/cr/uoregon/fullcit?p3018365.
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Thesis (Ph. D.)--University of Oregon, 2001.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 163-175). Also available for download via the World Wide Web; free to University of Oregon users.
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Le, Duc Thanh. "Algorithmes pour le (dés)assemblage d'objets complexes et applications à la biologie structurale." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2010. http://tel.archives-ouvertes.fr/tel-00538694.
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La compréhension et la prédiction des relations structure-fonction de protéines par des approches in sillico représentent aujourd'hui un challenge. Malgré le développement récent de méthodes algorithmiques pour l'étude du mouvement et des interactions moléculaires, la flexibilité de macromolécules reste largement hors de portée des outils actuels de modélisation moléculaire. L'objectif de cette thèse est de développer une nouvelle approche basée sur des algorithmes de planification de mouvement issus de la robotique pour mieux traiter la flexibilité moléculaire dans l'étude des interactions protéiques. Nous avons étendu un algorithme récent d'exploration par échantillonnage aléatoire, ML-RRT pour le désassemblage d'objets articulés complexes. Cet algorithme repose sur la décomposition des paramètres de configuration en deux sous-ensembles actifs et passifs, qui sont traités de manière découplée. Les extensions proposées permettent de considérer plusieurs degrés de mobilité pour la partie passive, qui peut Æetre poussée ou attirée par la partie active. Cet outil algorithmique a été appliqué avec succès pour l'étude des changements conformationnels de protéines induits lors de la diffusion d'un ligand. A partir de cette extension, nous avons développé une nouvelle méthode pour la résolution simultanée du séquenc¸age et des mouvements de désassemblage entre plusieurs objets. La méthode, nommée Iterative- ML-RRT, calcule non seulement les trajectoires permettant d'extraire toutes les pièces d'un objet complexe assemblé, mais également l'ordre permettant le désassemblage. L'approche est générale et a été appliquée pour l'étude du processus de dissociation de complexes macromoléculaires en introduisant une fonction d'évaluation basée sur l'énergie d'interaction. Les résultats présentés dans cette thèse montrent non seulement l'efficacité mais aussi la généralité des algorithmes proposés.
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Andersson, David. "Multivariate design of molecular docking experiments : An investigation of protein-ligand interactions." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-35736.
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To be able to make informed descicions regarding the research of new drug molecules (ligands), it is crucial to have access to information regarding the chemical interaction between the drug and its biological target (protein). Computer-based methods have a given role in drug research today and, by using methods such as molecular docking, it is possible to investigate the way in which ligands and proteins interact. Despite the acceleration in computer power experienced in the last decades many problems persist in modelling these complicated interactions. The main objective of this thesis was to investigate and improve molecular modelling methods aimed to estimate protein-ligand binding. In order to do so, we have utilised chemometric tools, e.g. design of experiments (DoE) and principal component analysis (PCA), in the field of molecular modelling. More specifically, molecular docking was investigated as a tool for reproduction of ligand poses in protein 3D structures and for virtual screening. Adjustable parameters in two docking software were varied using DoE and parameter settings were identified which lead to improved results. In an additional study, we explored the nature of ligand-binding cavities in proteins since they are important factors in protein-ligand interactions, especially in the prediction of the function of newly found proteins. We developed a strategy, comprising a new set of descriptors and PCA, to map proteins based on their cavity physicochemical properties. Finally, we applied our developed strategies to design a set of glycopeptides which were used to study autoimmune arthritis. A combination of docking and statistical molecular design, synthesis and biological evaluation led to new binders for two different class II MHC proteins and recognition by a panel of T-cell hybridomas. New and interesting SAR conclusions could be drawn and the results will serve as a basis for selection of peptides to include in in vivo studies.
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Malard, Florian. "Structural and dynamic studies of TCTP protein : deciphering a complex interaction network involved in tumor reversion." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS540.
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TCTP est une petite protéine globulaire (20~kDa) qui interagit avec de nombreux partenaires et qui est impliquée dans diverses fonctions cellulaires et physiologiques, avec un rôle bien documenté dans la réversion tumorale qui est un phénomène rare et spontané où une cellule cancereuse perd tout ou partie de son phénotype malin et retrouve des caractéristiques associées aux cellules bénignes telles que la sensibilité à l'apoptose. Dans les cellules cancéreuses, TCTP inhibe la dégradation de MDM2, diminuant ainsi les niveaux de p53 et favorisant le maintien et la progression du cancer. TCTP contient également un motif BH3-like connu pour réguler les membres de la famille Bcl-2 et elle interagit directement avec Bcl-xL et Mcl-1 pour renforcer leurs propriétés anti-apoptotiques. Dans la structure TCTP, le motif BH3-like n'est pas facilement accessible pour une interaction avec un partenaire. Conformément à son importance dans le maintien de la tumeur, TCTP est une cible pharmacologique validée dans le traitement du cancer et fait l’objet d’essais cliniques en cours avec une molécule d'abord connue comme anti-depresseur, la sertraline. Cependant, on en sait peu sur la structure de TCTP en complexe avec ses partenaires, ce qui entrave le développement de médicaments et ne permet pas de comprendre comment TCTP peut s'adapter à une telle variété de partenaires. Ainsi, nous avons étudié le mécanisme moléculaire par lequel TCTP s'associe à des protéines et à des ligands en utilisant diverses méthodes biophysiques (RMN, SAXS, CD, SEC, DSF...). Nous avons démontré que la protéine TCTP se lie à Bcl-xL et à Mcl-1 dans le sillon de liaison des motifs BH3. Dans les complexes, la région BH3-like est engagée dans l'interface intermoléculaire et la structure centrale de TCTP est déstabilisée dans un état de globule fondu (molten-globule). Nous avons en outre montré que seule une forme mineure pré-existante de TCTP, à savoir TCTP*, est compétente pour les interactions avec les partenaires Bcl-xL et Mcl-1. Dans TCTP*, la région BH3-like est détachée du domaine structuré et elle est accessible aux protéines Bcl-xL/Mcl-1 tandis qu'on retrouve un état globule fondu dans la partie globulaire de TCTP*. Nous avons également collecté des données d'interaction préliminaires entre TCTP et la sertraline, des ARN, la protéine YB-1 se liant à l'ARN et le domaine N-terminal de MDM2. Enfin, nous avons caractérisé TCTP phosphorylé (pTCTP) au résidu S46 en utilisant la Plk-1 car cette modification a un impact sur les interactions et est un marqueur de l'aggressivité tumorale. En résumé, ces travaux ont établi la versatilité de TCTP en terme de structure et ont montré que cette versatilité est indispensable pour exercer ses fonctions cellulaires. En conséquence, ceci devrait être pris en compte dans les stratégies de développement de nouvelles molécules thérapeutiques ciblant TCTPTCTP is a small (20~kDa) globular protein that interacts with many partners with consequences in various cellular and physiological functions, with well-documented roles in tumoral reversion program. Cells that undergo such program spontaneously loose their malignant phenotype and recover characteristics associated with benign cells, such as apoptosis. In cancer cells, TCTP inhibits MDM2 degradation, thus decreasing p53 levels and favoring tumor maintenance and progression. TCTP also contains a BH3-like motif known to regulate Bcl-2 family members and TCTP directly interacts with Bcl-xL and Mcl-1 to reinforce their pro-survival properties. In TCTP structure, the BH3-like motif is not readily accessible for interaction. Consistently with its importance in tumor maintenance, TCTP is a validated pharmacological target in cancer treatment with ongoing clinical trials using the TCTP-targeting antidepressant drug sertraline. However, little is known about TCTP structure in complex with partners, thus impeding the development of drugs and the understanding of how TCTP could adapt to its myriad of partners. Thus, we investigated the molecular mechanism by which TCTP associates with proteins and ligands using various biophysical methods (NMR, SAXS, CD, SEC, DSF...). We have demonstrated that full length TCTP binds to Bcl-xL and Mcl-1 in their BH3-binding groove. In the complexes, the TCTP BH3-like region is engaged in the intermolecular interface and the core TCTP structure is destabilized into a molten-globule (MG) state. We further showed that only a minor pre-existing form of TCTP, namely TCTP*, is competent for interactions with the Bcl-2 protein partners. In TCTP*, the BH3-like region is unpinned and accessible to Bcl-xL/Mcl-1 proteins and the core structure is also in MG state. We also collected preliminary interaction data between TCTP and sertraline, RNA, the RNA binding YB-1 protein and the MDM2 N-terminal domain. Finally, we characterized the Plk-1-mediated S46 phosphorylated TCTP (pTCTP), a marker of tumor aggressivity and its interaction properties. Overall, this work established the structural versatility of TCTP that is mandatory to exert its cellular functions and this versatility should be taken into account in drug-design strategies targeting TCTP
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Alavi, Sarah. "Synthese et evaluation biologique de derives de l’aminobenzosuberone, inhibiteurs puissants et selectifs de l’aminopeptidase N ou CD13." Thesis, Mulhouse, 2013. http://www.theses.fr/2013MULH4071/document.
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Le mode d’action des traitements médicaux fait généralement intervenir des interactions entre une (des) molécule(s) et une (des) cible(s) protéique(s) de l’organisme. Au sein de notre équipe, le choix s’est porté vers l’APN, protéine connue depuis les années 2000, pour être impliquée dans les processus d’angiogenèse i.e. la formation de nouveaux vaisseaux sanguins à partir de vaisseaux préexistants, et de migration cellulaire. Compte tenu de la pertinence thérapeutique des fonctions de l’APN et de leur validation lors d’études in vivo, la conception de voies de synthèse simples et efficaces menant à l’inhibiteur le plus puissant et sélectif de l’APN est devenu un des objectifs premier du laboratoire : 3 voies de synthèses sont décrites. Par ailleurs, notre laboratoire s’est intéressé à une nouvelle classe de composés comportant un groupement ferrocényle. En effet, les composés organométalliques suscitent un intérêt grandissant dans le développement de thérapies anticancéreuse ou encore les maladies tropicales. Ses possibilités réactionnelles étendues combinées à ses remarquables propriétés électrochimiques donnent lieu à des molécules nouvelles aux propriétés biologiques étonnantes. Ayant développé la molécule la plus puissante vis-à-vis de l’APN, ses impressionnantes propriétés inhibitrices peuvent être exaltées en créant des molécules à activité duale : inhibitrice de l’APN et cytotoxique vis-à-vis des cellules tumorales. La synthèse de ces composés hybrides ainsi que l’évaluation de leurs effets envers deux cibles, l’APN (porcine et d’Escherichia coli) et les cellules HT1080 (cellules de type fibrosarcome exprimant fortement l’APN), sont décrites dans cette thèseAPN/CD13, a zinc dependent metallo-peptidase ectoenzyme widespread in human tissues is emerging as a new target in cancer therapy. Indeed several studies indicate that APN/CD13 plays an active role in angiogenesis and tumor metastasis. We already prepared a series of (±)-1,4-disubstituted-7-amino-benzocyclohepten-6-ones and discovered the extraordinary inhibitory power of the 1-bromo-4-phenyl derivative (Ki = 60 pM) on mammalian APN/CD13. As recent crystallographic works in collaboration with the Paul Scherrer Institut have revealed that only the (S) enantiomer was efficiently binded to the enzyme active site, we recently developed a new synthetic pathway to prepare this optically pure molecule in benzo-oxepine series. In parallel we prepare analogs equipped with at least one ferrocenyl moiety of potential intrinsic additional cytotoxicity
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Berg, Lotta. "Exploring non-covalent interactions between drug-like molecules and the protein acetylcholinesterase." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-129900.
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The majority of drugs are small organic molecules, so-called ligands, that influence biochemical processes by interacting with proteins. The understanding of how and why they interact and form complexes is therefore a key component for elucidating the mechanism of action of drugs. The research presented in this thesis is based on studies of acetylcholinesterase (AChE). AChE is an essential enzyme with the important function of terminating neurotransmission at cholinergic synapses. AChE is also the target of a range of biologically active molecules including drugs, pesticides, and poisons. Due to the molecular and the functional characteristics of the enzyme, it offers both challenges and possibilities for investigating protein-ligand interactions. In the thesis, complexes between AChE and drug-like ligands have been studied in detail by a combination of experimental techniques and theoretical methods. The studies provided insight into the non-covalent interactions formed between AChE and ligands, where non-classical CH∙∙∙Y hydrogen bonds (Y = O or arene) were found to be common and important. The non-classical hydrogen bonds were characterized by density functional theory calculations that revealed features that may provide unexplored possibilities in for example structure-based design. Moreover, the study of two enantiomeric inhibitors of AChE provided important insight into the structural basis of enthalpy-entropy compensation. As part of the research, available computational methods have been evaluated and new approaches have been developed. This resulted in a methodology that allowed detailed analysis of the AChE-ligand complexes. Moreover, the methodology also proved to be a useful tool in the refinement of X-ray crystallographic data. This was demonstrated by the determination of a prereaction conformation of the complex between the nerve-agent antidote HI-6 and AChE inhibited by the nerve agent sarin. The structure of the ternary complex constitutes an important contribution of relevance for the design of new and improved drugs for treatment of nerve-agent poisoning. The research presented in the thesis has contributed to the knowledge of AChE and also has implications for drug discovery and the understanding of biochemical processes in general.
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Ju, Yue. "MASS SPECTROMETRIC STUDY OF PROTEIN AND PROTEIN LIGAND COMPLEXES." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449219266.
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Yang, Hui. "Theoretical Studies of Molecular Recognition in Protein-Ligand and Protein-Protein Complexes." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1282339026.
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Stauch, Benjamin H. "Methods for the investigation of protein-ligand complexes." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648520.
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Scaffidi, Salvatore. "Biophysical Techniques for the Investigation of Protein-Ligand Complexes." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673608.
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Once a target is identified and characterized, the long pathway to develop a drug starts. In this process, biophysical methods have an important part to play and nowadays are firmly combined at several stages. In this scenario, using biophysical techniques, the main objective of this work is based on the identification and characterization of small molecules with the ability to bind several proteins.
Fbw7 is an E3 ligase with an important role in cancer. However, until now no Fbw7 small molecules ligands have been identified. In this thesis we have performed a FBDD program in order to identify fragments able to bind to this E3 ligase. These fragments could be employed as starting points to elucidate the best strategy to target Fbw7 and to build novel PROTAC molecules.
Due to the poor aqueous solubility of retinoids, evolution has tuned their binding to cellular proteins to address specialized physiological roles by modulating uptake, storage, and delivery to specific targets. In this thesis, we have disentangled the structure−function relationships of these protein class and disclose clues for engineering selective carriers.
Given the binding mode of fragments to a target of interest, optimization of the fragments can result laborious, difficult and time consuming. In this thesis, small molecules binding to Brd4(BD1), identified by the automated fragment evolution platform developed by our group, have been assayed and the platform validated.Una vez que se identifica y caracteriza una proteina, comienza el largo camino para desarrollar un fármaco. En este proceso, los métodos biofísicos tienen un papel importante que jugar y hoy en día se combinan firmemente en varias etapas. En este escenario, utilizando técnicas biofísicas, el principal objetivo de este trabajo se basa en la identificación y caracterización de pequeñas moléculas con capacidad para unirse a varias proteínas. Fbw7 es una ligasa E3 con un papel importante en el cáncer. Sin embargo, hasta ahora no se han identificado ligandos de moléculas pequeñas de Fbw7. En esta tesis hemos realizado un programa FBDD para identificar fragmentos capaces de unirse a esta ligasa E3. Estos fragmentos podrían emplearse como puntos de partida para dilucidar la mejor estrategia para apuntar a Fbw7 y construir nuevas moléculas PROTAC. Debido a la escasa solubilidad en agua de los retinoides, la evolución ha ajustado su unión a proteínas celulares para abordar funciones fisiológicas especializadas mediante la modulación de la captación, el almacenamiento y la entrega a sitios específicos . En esta tesis, hemos desenredado las relaciones estructura-función de estas clases de proteínas y hemos revelado pistas para diseñar transportadores selectivos. Dado el modo de unión de los fragmentos a un objetivo de interés, la optimización de los fragmentos puede resultar laboriosa, difícil y requiere mucho tiempo. En esta tesis, se ha hecho un ensayo sobre pequeñas moléculas que se unen a Brd4 (BD1), identificadas por la plataforma de evolución de fragmentos automatizada desarrollada por nuestro grupo, y se ha validado la plataforma.
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Read, Stuart Hamilton. "Production and function of a soluble c-Kit molecule." Title page, abstract and contents only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phr2845.pdf.
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"Research conducted at the Department of Haematology, Hanson Centre for Cancer Research, Institute of Medical and Veterinary Science."--T.p. Includes bibliographical references (leaves 170-214). Elevated levels of receptor tyrosine kinases have been implicated in carcinogenesis. It is possible that high expression of c-Kit by the leukaemic cell provides them with a growth advantage over their normal counterparts in the bone marrow microenvironment. Thus, a means of inhibiting the interaction of c-Kit on these cells with ligand Steel Factor may remove proliferation and survival signals. Main aim of the study was to produce a biological inhibitor of this interaction and evaluate its ability to prevent ligand Steel Factor from binding to c-Kit on live cells.
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Woods, Christopher J. "The development of free energy methods for protein-ligand complexes." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396741.
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Han, Yaohua. "Quantum Chemical Study of Molecular Recognition in Protein-Ligand Complexes." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1373313907.
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Wang, Xu. "Computational Studies of Structures and Binding Properties of Protein-Ligand Complexes." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207100.
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Proteins are dynamic structural entities that are involved in many biophysical processes through molecular interactions with their ligands. Protein-ligand interactions are of fundamental importance for computer-aided drug discovery. Due to the fast development in computer technologies and theoretical methods, computational studies are by now able to provide atomistic-level description of structures, thermodynamic and dynamic properties of protein-ligand systems, and are becoming indispensable in understanding complicated biomolecular systems. In this dissertation, I have applied molecular dynamic (MD) simulations combined with several state of the art free-energy calculation methodologies, to understand structures and binding properties of several protein-ligand systems. The dissertation consists of six chapters. In the first chapter, I present a brief introduction to classical MD simulations, to recently developed methods for binding free energy calculations, and to enhanced sampling of configuration space of biological systems. The basic features, including the Hamiltonian equations, force fields, integrators, thermostats, and barostats, that contribute to a complete MD simulation are described in chapter 2. In chapter 3, two classes of commonly used algorithms for estimating binding free energies are presented. I highlight enhanced sampling approaches in chapter 4, with a special focus on replica exchange MD simulations and metadynamics, as both of them have been utilized in my work presented in the chapter thereafter. In chapter 5, I outlined the work in the 5 papers included in the thesis. In paper I and II, I applied, respectively, the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) and alchemical free energy calculation methods to identify the molecular determinant of the affibody protein ZAb3 bound to an amyloid b peptide, and to investigate the binding profile of the positive allosteric modulator NS-1738 with the α7 acetylcholine-binding protein (α7-AChBP protein); in paper III and VI, unbiased MD simulations were integrated with the well-tempered metadynamics approach, with the aim to reveal the mechanism behind the higher selectivity of an antagonist towards corticotropin-releasing factor receptor-1 (CRF1R) than towards CRF2R, and to understand how the allosteric modulation induced by a sodium ion is propagated to the intracellular side of the d-opioid receptor; in the last paper, I proved the structural heterogeneity of the intrinsically disordered AICD peptide, and then employed the bias-exchange metadynamics and kinetic Monte Carlo techniques to understand the coupled folding and binding of AICD to its receptor Fe65-PTB2. I finally proposed that the interactions between AICD and Fe65-PTB2 take place through an induced-fit mechanism. In chapter 6, I made a short conclusion of the work, with an outlook of computational simulations of biomolecular systems.QC 20170516
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Lengqvist, Johan. "Native protein mass spectrometry of nuclear receptor-ligand and enzyme-substrate complexes /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-116-4/.
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Cioffi, Marina. "Structure determination of protein-ligand complexes using 1H-NMR chemical shift changes." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489716.
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Chapter 1 reviews the experimental and computational techniques available for the structure determination of protein-ligand complexes at atomic resolution. Chapter 2 describes a new method for determining three-dimensional solution structures of protein-ligand complexes using experimentally determined complexation-induced changes in ¹H NMR chemical shift (CIS). The method has been tested using the complex formed by the protein Neocarzinostatin and four synthetic chromophore analogues. The experimental CIS values were used in a continuous direct structure refinement process based on genetic algorithms to sample conformational space. The calculated structure agrees well with the NMR solution structure of the complex indicating the potential of this approach for structure determination. Chapter 3 reports an analysis of the effects of protein flexibility on the accuracy of 3D structures determined using the CIS-based approach. The effects of protein conformational mobility have been investigated. The results indicated that loop movement has a significant impact on the quality of the structure generated by the CIS structure determination methodology. Chapter 4 introduces a first attempt to validate the CIS-based approach on a set of complexes containing ligands, with a range of anisotropic functional groups, molecular size and flexibility. For all the cases analyzed, it was possible to identify the protein binding site and in some cases the orientation of the ligand in the binding site was also accurately predicted. Chapter 5 reports binding studies for the complexes of the protein Barnase with ligand 3-GMP, d(GpC) and d(CGAC). The mononucleotide did not show any binding even when changing pH conditions. However, binding was observed for the dinucleotide and tetranucleotide. NMR titration experiments supported by structure determination experiments show that in both cases the ligand binds in the G-recognition binding site, in contrast with previously published X-ray experiments, where d(GpC) tends to occupy secondary subsite as a result of crystal packing.
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Toschi, Francesca. "The computational investigation of protein/ligand complexes : implications for rational drug design." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/378844/.
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Kern, Petra Susanne. "Investigations on truncated protein models : development of tools for molecular dynamics simulations of protein-ligand complexes /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10848.
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Frieg, Benedikt [Verfasser], and Birgit [Gutachter] Strodel. "Integrative modeling of function-associated molecular recognition in protein-ligand, protein-peptide, and protein-protein complexes / Benedikt Frieg ; Gutachter: Birgit Strodel." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2020. http://d-nb.info/1203872445/34.
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Hopper, Jonathan T. S. "Studying protein-ligand complexes in the gas-phase using ion mobility-mass spectrometry." Thesis, University of Nottingham, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.576159.
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This thesis presents studies which investigate the application of electrospray ionisation-mass spectrometry (ESI-MS) to non-covalent protein-ligand complexes. The structural effect of desolvation on protein-ligand (P-L) complexes has been a hotly debated issue in this field and has been examined in this work. Single point mutagenesis has allowed specific non-covalent interactions to be probed as well as their contribution to gas-phase protein- ligand stability. Results suggest that these specific interactions are preserved in the gas-phase using ESI. Other solution based effects that result from ligand binding, such as increased protein structural stability, was also confirmed in the gas-phase. A combination of collisional activation and ion mobility spectrometry is presented as an approach capable of probing such subtle stability differences. Some discrepancies between the behaviour of protein- ligand complexes in solution and the gas-phase are also presented and highlight potential areas of caution in certain biological systems. Common alkali metal adducts have been shown to severely decrease the stability of protein-ligand complexes in the gas-phase, possibly by a Coulomb assisted dissociation mechanism. Novel approaches to allow greater control of charge state distributions, without the requirement of instrumental modifications, are also presented. Reducing the charge state of protein complexes in the gas-phase allows weak interactions to be more readily preserved and more accurate affinity measurements to be made. The approach is also confirmed to reduce the amount of alkali metal adduction observed in protein ions generated by ESI.
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Fischer, Nina M. [Verfasser], and Oliver [Akademischer Betreuer] Kohlbacher. "Modeling Flexibility of Protein-DNA and Protein-Ligand Complexes using Molecular Dynamics / Nina M. Fischer ; Betreuer: Oliver Kohlbacher." Tübingen : Universitätsbibliothek Tübingen, 2013. http://d-nb.info/1162896728/34.
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Boukharta, Lars. "Computational Modelling of Ligand Complexes with G-Protein Coupled Receptors, Ion Channels and Enzymes." Doctoral thesis, Uppsala universitet, Beräknings- och systembiologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-212103.
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Accurate predictions of binding free energies from computer simulations are an invaluable resource for understanding biochemical processes and drug action. The primary aim of the work described in the thesis was to predict and understand ligand binding to several proteins of major pharmaceutical importance using computational methods. We report a computational strategy to quantitatively predict the effects of alanine scanning and ligand modifications based on molecular dynamics free energy simulations. A smooth stepwise scheme for free energy perturbation calculations is derived and applied to a series of thirteen alanine mutations of the human neuropeptide Y1 G-protein coupled receptor and a series of eight analogous antagonists. The robustness and accuracy of the method enables univocal interpretation of existing mutagenesis and binding data. We show how these calculations can be used to validate structural models and demonstrate their ability to discriminate against suboptimal ones. Site-directed mutagenesis, homology modelling and docking were further used to characterize agonist binding to the human neuropeptide Y2 receptor, which is important in feeding behavior and an obesity drug target. In a separate project, homology modelling was also used for rationalization of mutagenesis data for an integron integrase involved in antibiotic resistance. Blockade of the hERG potassium channel by various drug-like compounds, potentially causing serious cardiac side effects, is a major problem in drug development. We have used a homology model of hERG to conduct molecular docking experiments with a series of channel blockers, followed by molecular dynamics simulations of the complexes and evaluation of binding free energies with the linear interaction energy method. The calculations are in good agreement with experimental binding affinities and allow for a rationalization of three-dimensional structure-activity relationships with implications for design of new compounds. Docking, scoring, molecular dynamics, and the linear interaction energy method were also used to predict binding modes and affinities for a large set of inhibitors to HIV-1 reverse transcriptase. Good agreement with experiment was found and the work provides a validation of the methodology as a powerful tool in structure-based drug design. It is also easily scalable for higher throughput of compounds.
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Almlöf, Martin. "Computational Methods for Calculation of Ligand-Receptor Binding Affinities Involving Protein and Nucleic Acid Complexes." Doctoral thesis, Uppsala University, Department of Cell and Molecular Biology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7421.
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The ability to accurately predict binding free energies from computer simulations is an invaluable resource in understanding biochemical processes and drug action. Several methods based on microscopic molecular dynamics simulations exist, and in this thesis the validation, application, and development of the linear interaction energy (LIE) method is presented.
For a test case of several hydrophobic ligands binding to P450cam it is found that the LIE parameters do not change when simulations are performed with three different force fields. The nonpolar contribution to binding of these ligands is best reproduced with a constant offset and a previously determined scaling of the van der Waals interactions.
A new methodology for prediction of binding free energies of protein-protein complexes is investigated and found to give excellent agreement with experimental results. In order to reproduce the nonpolar contribution to binding, a different scaling of the van der Waals interactions is neccesary (compared to small ligand binding) and found to be, in part, due to an electrostatic preorganization effect not present when binding small ligands.
A new treatment of the electrostatic contribution to binding is also proposed. In this new scheme, the chemical makeup of the ligand determines the scaling of the electrostatic ligand interaction energies. These scaling factors are calibrated using the electrostatic contribution to hydration free energies and proposed to be applicable to ligand binding.
The issue of codon-anticodon recognition on the ribosome is adressed using LIE. The calculated binding free energies are in excellent agreement with experimental results, and further predict that the Leu2 anticodon stem loop is about 10 times more stable than the Ser stem loop in complex with a ribosome loaded with the Phe UUU codon. The simulations also support the previously suggested roles of A1492, A1493, and G530 in the codon-anticodon recognition process.
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Heinzerling, Lennart Erik [Verfasser], and Matthias [Akademischer Betreuer] Rarey. "Accelerating Force Field-Based Optimizations of Protein-Ligand Complexes / Lennart Erik Heinzerling. Betreuer: Matthias Rarey." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2015. http://d-nb.info/1069986305/34.
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Almlöf, Martin. "Computational methods for calculation of Ligand-Receptor binding affinities involving protein and nucleic acid complexes /." Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7421.
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Meyder, Agnes [Verfasser]. "Structure Profiling and Geometric Optimization of Protein-Ligand Complexes for the Scoring Function HYDE / Agnes Meyder." Hamburg : Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky, 2020. http://d-nb.info/1221721003/34.
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Göth, Melanie [Verfasser]. "Investigation of Protein-Ligand Complexes by Native Mass Spectrometry and Ion Mobility-Mass Spectrometry / Melanie Göth." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1149050594/34.
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Nguyen, Huynh Nha Thi. "Développements en spectrométrie de masse pour l’étude des complexes biologiques." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF045/document.
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L’élucidation des interactions non-covalentes des complexes biologiques revêt d’une importance majeure dans la compréhension du fonctionnement cellulaire. L’objectif de ce travail de thèse est d’approfondir les développements de la spectrométrie de masse (MS) pour l’étude de ces complexes, que ce soit par MALDI-MS (la désorption-ionisation laser assistée par matrice) ou par ESI-MS (l’ionisation électrospray). Ce travail s’est articulé autour de trois axes : i) étude de la stœchiométrie et de la topologie du complexe SAGA HAT (Spt-Ada-Gcn5 Acétyltransferase, module Histone Acétyl Transferase) par pontage chimique couplé à la MS ; ii) suivi de la dimérisation des complexes formés par RAR-RXR (récepteur de l’acide rétinoïque - récepteur X des rétinoïdes) avec différents ADNs ; iii) mesure de la constante de dissociation des complexes RXR-ligand. Les méthodologies développées ont permis de repousser le potentiel de la MS et d’obtenir des informations structurales des complexes biologiquesElucidation of non-covalent interactions of biological complexes takes on great importance for the understanding of cellular function. The purpose of this thesis is a further development of mass spectrometry (MS) for the study of these complexes, either by MALDI-MS (matrix-assisted laser desorption-ionization) or by ESI-MS (electrospray ionization). This work was focused on three main lines: i) study of the stoichiometry and the topology of SAGA HAT (Spt-Ada-Gcn5 Acetyltransferase, Histone Acetyl Transferase module) complex by chemical cross-linking coupled to MS; ii) monitoring the dimerization of the complexes formed by RAR-RXR (retinoic acid receptor - retinoid X receptor) with different DNAs; iii) measuring the dissociation constant of RXR-ligand complexes. The developed methodologies made it possible to expand the potential of MS and get insight into structure of biological complexes
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Krotzky, Timo [Verfasser], and Gerhard [Akademischer Betreuer] Klebe. "Methods for the Efficient Comparison of Protein Binding Sites and for the Assessment of Protein-Ligand Complexes / Timo Krotzky. Betreuer: Gerhard Klebe." Marburg : Philipps-Universität Marburg, 2015. http://d-nb.info/1076865607/34.
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Davis, Caroline M. "Investigation and Characterisation of Protein-Ligand Interactions: SRA-Ribonucleic Acid Recognition and Anti-Microbial Drug Discovery." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1437779075.
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Altman, Michael Darren. "Computational ligand design and analysis in protein complexes using inverse methods, combinatorial search, and accurate solvation modeling." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36258.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2006.Vita.
Includes bibliographical references (p. 207-230).
This thesis presents the development and application of several computational techniques to aid in the design and analysis of small molecules and peptides that bind to protein targets. First, an inverse small-molecule design algorithm is presented that can explore the space of ligands compatible with binding to a target protein using fast combinatorial search methods. The inverse design method was applied to design inhibitors of HIV-1 protease that should be less likely to induce resistance mutations because they fit inside a consensus substrate envelope. Fifteen designed inhibitors were chemically synthesized, and four of the tightest binding compounds to the wild-type protease exhibited broad specificity against a panel of drug resistance mutant proteases in experimental tests. Inverse protein design methods and charge optimization were also applied to improve the binding affinity of a substrate peptide for an inactivated mutant of HIV-1 protease, in an effort to learn more about the thermodynamics and mechanisms of peptide binding. A single mutant peptide calculated to have improved binding electrostatics exhibited greater than 10-fold improved affinity experimentally.
(cont.) The second half of this thesis presents an accurate method for evaluating the electrostatic component of solvation and binding in molecular systems, based on curved boundary-element method solutions of the linearized Poisson-Boltzmann equation. Using the presented FFTSVD matrix compression algorithm and other techniques, a full linearized Poisson-Boltzmann equation solver is described that is capable of solving multi-region problems in molecular continuum electrostatics to high precision.
Michael Darren Altman.
Ph.D.
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Dyachenko, Andrey. "Molecular recognition in gas phase: theoretical and experimental study of non-covalent protein-ligand complexes by mass-spectrometry." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/113301.
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In the present thesis we have explored different factors that impede accurate quantitative description of non-covalent protein-protein and protein-ligand interactions and design of new potent and specific binders from the scratch. Firstly, we addressed the role of solvent in the mechanism of non-covalent interactions. Secondly, we tackled the question about the intrinsic conformational flexibility of the protein molecules and the part it plays in weak interactions between proteins.
In the first part of the thesis we studied the interactions of vascular endothelial growth factor (VEGF) protein with five cyclic peptides in solution and gas phase. The results showed that affinities of five ligands to VEGF in solution and gas phase are ranked in inversed order. That is, the that has the highest affinity in solution (as shown by chemical shift perturbation NMR and isothermal titration calorimetry) forms the weakest complex with VEGF in gas phase, and vice versa. We compared gas-phase and solution binding affinities of of five peptides and made qualitative conclusions about the role of the solvent in protein-ligand interactions.
In order to obtain more quantitative information about the gas-phase behavior of non-covalent complexes we have developed a combined experimental/theoretical approach to study the energetics of collisional activation of the ion prior to dissociation. We applied developed strategy to model CID in traveling wave ion guide (TWIG) collision cell. We validated the model on the CID of leu-enkephalin peptide and then applied developed strategy to five non-covalent protein-peptide complexes and found activation energies of their dissociation reactions.
Next we applied ESI native MS to study the allosteric interactions between the molecular chaperonin GroEL and ATP. The obtained data allowed to construct a scheme of conformational transition of GroEL upon binding of ATP and distinguish between two different cooperativity models, providing strong arguments in favor of Monod-Wyman-Changeux (MWC) model.
Finally, be studied the backbone dynamics of VEGF with a combination of NMR relaxation and all-atom force-field based normal mode analysis (NMA). We showed that combination of experimental and computational approach allows to identify flexible zones with higher level of confidence. We also found out that residues, that are involved VEGF-receptor interactions, reside in or close to the flexible zones, suggesting the critical role conformational plasticity plays in the non-covalent protein-protein interactions.Las biomoléculas de los organismos vivos realizan sus funciones principalmente a través de interacciones débiles reversibles entre ellas. La transducción de señal, la replicación de ADN/ARN, otros procesos enzimáticos y, virtualmente, cualquier otro proceso involucrado en las funciones vitales de cualquier organismo vivo (de las simples amebas, al complejo ser humano), requiere que las moléculas “hablen” entre ellas. Dicho lenguaje se basa en interacciones no covalentes. La flexibilidad conformacional es una propiedad esencial de las grandes biomoléculas, y muchas de las funciones desempeñadas por proteínas se basan en su capacidad para cambiar de conformación en respuesta a un factor externo. Geométricamente hablando, la presencia de flexibilidad en una proteína obstaculiza el diseño racional de medicamentos porque posibilita la existencia de un número muy elevado de conformaciones de dicha proteína. Por este motivo, cualquier información sobre la flexibilidad de una proteína es sumamente valiosa para la comprensión de PPI y PLI y para el diseño racional de medicamentos. Los capítulos 1-3 de la presente tesis versan sobre la solvatación, mientras que la flexibilidad se estudiara en el capitulo 4.
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Green, David Francis 1975. "Optimization of electrostatic binding free energy : applications to the analysis and design of ligand binding in protein complexes." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16888.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2002.Vita.
Includes bibliographical references (p. 279-298).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Electrostatic interactions play an important role in determining the energetics of association in biomolecular complexes. Previous work has shown that, within a continuum electrostatic model, for any given complex there exists a ligand charge distribution which optimizes the electrostatic binding free energy - the electrostatic complement of the target receptor. This electrostatic affinity optimization procedure was applied to several systems both in order to understand the role of electrostatic interactions in natural systems and as a tool in the design of ligands with improved affinity. Comparison of the natural and optimal charges of several ligands of glutaminyl-tRNA synthetase from E. coli, an enzyme with a strong natural requirement for specificity, shows remarkable similarity in many areas, suggesting that the optimization of electrostatic interactions played a role in the evolution of this system. The optimization procedure was also applied to the design of improvements to two inhibitors of HIV-1 viral-cell membrane fusion. Two tryptophan residues that are part of a D-peptide inhibitor were identified as contributing most significantly to binding, and a novel computational screening procedure based on the optimization methodology was developed to screen a library of tryptophan derivatives at both positions. Additionally, the optimization methodology was used to predict four mutations to standard amino acids at three positions on 5-Helix, a protein inhibitor of membrane fusion. All mutations were computed to improve the affinity of the inhibitor, with a five hundred-fold improvement calculated for one triple mutant.
(cont.) In the complex of b-lactamase inhibitor protein with TEM1 b-lactamase, a novel type of electrostatic interaction was identified, with surface exposed charged groups on the periphery of the binding interface projecting significant energetic effects through as much as 10 A of solvent. Finally, a large number of ab initio methods for determining partial atomic charges on small molecules were evaluated in terms of their ability to reproduce experimental values in continuum electrostatic calculations, with several preferred methods identified.
by David Francis Green.
Ph.D.
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Aguirre, Clémentine. "Analyse quantitative des perturbations de déplacement chimique pour la détermination de structures tridimensionnelles de complexes protéine-ligand." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10217/document.
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Les interactions intermoléculaires entre une protéine et ses différents partenaires représentent des cibles de plus en plus prisées pour l'élaboration de composés thérapeutiques capables d'intervenir dans des processus biologiques. La méthode FBDD (Fragment-Based Drug Design) permet de concevoir des molécules bioactives tels que des inhibiteurs, à partir de la structure tridimensionnelle du complexe formé entre la protéine et une molécule fragment. Dans le cadre de ce projet de thèse nous proposons d'utiliser le déplacement chimique pour l'étude des structures 3D de ces complexes protéine-ligand. Nous nous focaliserons sur la mesure des perturbations de déplacement chimique CSP (Chemical Shift Perturbations) des atomes d'une protéine cible, induites par la liaison d'un fragment. Nous démontrerons la puissance de cet outil RMN à travers la simulation des CSP induits par l'interaction d'un fragment sur une protéine cible et leur comparaison aux CSP expérimentaux. L'analyse sera réalisée sur deux protéines cibles et la comparaison des données expérimentales et simulées permettra dans un premier temps de mettre en évidence un réarrangement structural de la protéine Bcl-xL lors de son interaction avec un fragment. Puis, dans un second temps, nous montrerons que cette analyse quantitative des CSP peut permettre de déterminer l'orientation des fragments dans le site d'interaction de la protéine PRDX5. Nous comparerons alors les performances de la méthode pour différents types de protons proposant ainsi de nouvelles pistes pour la compréhension du comportement des CSP vis-à-vis de leurs contributions électroniquesIntermolecular interactions between protein and its partners represent highly attractive targets for the elaboration of therapeutic compounds abble to interfere in biological processes. A novel approach in drug design called Fragment-Based Drug Design (FBDD) consists of designing bioactive molecules like inhibitors, from the 3D structure of the complex formed between a protein and a fragment molecule (MW < 300g/mol). Here we suggest using the chemical shift, to study these protein-ligand structures. We will particularly focus on the measurement of Chemical Shift Perturbations (CSP) induced by the fragment-binding on protein’s nuclei. We will evidence the potency of this NMR tool through simulation of CSP induced by fragment interaction on protein target and the comparison with experimental CSP. Two protein targets will be used and the comparison between experimental and simulated data will evidence on one hand, the structural rearrangement of the protein Bcl-xL upon fragment-binding. On the other hand, we will demonstrate that this quantitative use of CSP is unable to determinate fragment orientations inside the protein PRDX5 binding site. We will compare the performances of the method for different kinds of protein and proposing answers to better understand the behaviour of CSP toward their different electronic contributions
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Martinelli, Nicolas. "Structure et fonction d'un ligand d'ESCRT-III, LgD/CC2D1A." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00769410.
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Le bourgeonnement est l'étape finale du cycle viral du virus VIH. Les particules virales vont devoir modifier la topologie de la membrane plasmique afin de promouvoir leur libération dans le milieu extracellulaire ; cette étape est réalisée par le recrutement de protéines ESCRT (en particulier CHMP4 et CHMP2) au point de bourgeonnement. A ce jour, les détails moléculaires de ce recrutement sont méconnus. Lethal Giant Discs (LgD) a été décrite dans la littérature comme un régulateur du traffic endosomal, et une interaction avec CHMP4B a été proposée pour l'orthologue humain CC2D1A. Un point majeur de ce travail aura été de caractériser l'interaction CC2D1A.CHMP4B, mais également de mieux comprendre l'organisation de la protéine. En particulier j'ai résolu la structure d'un fragment de LgD à 2.4 Å, comprenant une région hélicale et un domaine C2 en c-terminal. En outre, nous montrons que CC2D1A inhibe la capacité de CHMP4B à polymériser in vitro. A partir d'une structure cristallographique de CHMP4B et de données biochimiques, nous montrons que le site d'interaction de CC2D1A sur CHMP4B est impliqué dans la polymérisation de CHMP4B, et important pour la fonction de la protéine dans le contexte du bourgeonnement du HIV. Un projet parallèle m'a également conduit à définir un protocole de purification de la protéine CHMP2B recombinante sous forme monomérique, cet isoforme ayant été récemment impliqué dans la formation de structures tubulaires à la membrane plasmique et dans des activités de scission membranaire. En particulier, j'ai pû caractériser la protéine en présence de liposomes et préciser de nouveaux partenaires cellulaires.
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Stojko, Johann. "Nouvelles méthodologies en spectrométrie de masse native et mobilité ionique pour la caractérisation structurale de macrobiomolécules et de leurs complexes associés." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF003/document.
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Ce travail de thèse porte sur le développement de méthodes en spectrométrie de masse (MS) et mobilité ionique (IM-MS) supramoléculaires pour la caractérisation fine de complexes protéine-ligand et d’assemblages protéiques hétérogènes de hauts poids moléculaires. L’optimisation instrumentale apportée à l’étude de ces systèmes, permet d’étendre le potentiel de ces deux approches en biologie structurale. Le criblage de complexes protéine-ligand permet ici une détermination de leurs propriétés d’interaction et la mise en évidence de subtils changements de conformation induits, pouvant être suivis au cours du temps. L’application de ce couplage à l’analyse de complexes multi-protéiques, réfractaires aux techniques conventionnelles, donne accès à la topologie de ces assemblages, facilitant la proposition de modèles structuraux. Enfin, l’apport récent de la haute résolution en MS native est ici illustré à travers l’étude de protéines complexes et hétérogènes : les anticorps thérapeutiques et leurs conjugués. Ces développements permettent de repousser certaines limites en MS native et IM-MS native, élargissant leurs perspectives d’application dans la recherche et l’industrie pharmaceutiqueThis PhD thesis aims at developing methods in native mass spectrometry (MS) combined with ion mobility (IM-MS) to characterize protein-ligand complexes and large protein assemblies. Fine-tuning of instrumental settings allowed expanding the scope of these approaches in structural biology. Real-time monitoring of protein-ligand complexes by native MS and IM-MS enabled to screen their binding properties while depicting subtle conformational changes induced upon binding. Applying these methods to refractory multi-protein complexes provided insights about their topology, making structural modeling easier. Finally, benefits from high-resolution native MS were highlighted through the characterization of heterogeneous systems, including monoclonal antibodies and their drug conjugates. Here, these developments enable to push some technical limits one step forward, increasing the potential of native MS and IM-MS both in academic research and pharmaceutical industry
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Dogra, Navneet. "INVESTIGATING PROTEIN - BILAYER COMPLEXES: A STUDY OF LIGAND - RECEPTOR INTERACTIONS AT MODEL MEMBRANE SURFACE BY USING ELECTRONIC ABSORPTION SPECTROSCOPY AND FLUORESCENCE RESONANCE ENERGY TRANSFER." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/dissertations/812.
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The main aim of work presented here is to design, develop and characterize a colorimetric model membrane (liposome) systems, which can bind with proteins, enzymes, bacteria, virus and other biomolecules. PDA molecules are utilized as a scaffold for the bilayer membrane, and a colorimetric assay is carried out. The holy grail of present work contributes towards the better understanding of protein interactions with the cell bilayer surface. Chapter 1 introduces a brief history on the advent of bilayer systems for cellular research exploration. We presented a literature survey about how liposome systems are used as a complementary technique to understand the fundamental principles of cellular membrane functions. Furthermore, we describe about membrane protein functions and recent findings on how proteins interact with the cell membrane. Finally, we explain conjugated systems and their exploration in bilayer membrane as a colorimetric scaffold. We also touch bases with major fluorescence techniques used in our experiments. Chapter 2 provides details on the preparation protocols of liposome and liposome-protein complexes. We confirmed protein-bilayer interactions by monitoring FRET between PDA and rhodamine molecules. Furthermore, we performed streptavidin-biotin binding studies on the PDA bilayer. Protein binding changed the spectral overlap (J) between PDA and rhodamine, which ultimately increased the fluorescence emission of rhodamine. The goal of performing these studies was to present a complete protocol for the preparation of liposome and protein-liposome complex. In chapter 3, we investigate how proteins bind on the cell membrane. Additionally, we propose a model of protein-bilayer complex. We reported that, by harnessing cell bilayer with specific bio-molecules, we monitored protein--bilayer, protein--protein and enzyme--substrate signal transduction. We have developed a colorimetric system for monitoring vital stimulations occur on the liposomal membrane surface. Bilayer was modified to covalently bind the amino group of lysine residues present on protein molecules. These bio-molecular interactions on bilayer surface provide differential stimulus, which turned out to be the major cause of differential spectroscopic signals depending upon size and shape of the protein bounded to the bilayer. Polydiacetylene (PDA) liposomes are the core of our color based system. These liposomes are used to monitor subtle interactions on the bilayer surface. We have also developed a semi-quantitative method based on the colorimetric response of PDA liposomes; we were able to detect protein molecules at sub-nanomolar concentrations in the solution. It's capability of distinguishing protein molecules based on their chemical and physical interactions to bilayer contributes towards the identity of our system. Interestingly, our mass spectroscopic data suggested non-specific enzymatic cleavage of membrane-bound proteins. These fragments were not present in bulk protein cleavage. We also proposed a model that depicts the covalent binding of protein at the bilayer of liposomes. These studies are intended to investigate protein-bilayer and enzyme-protein interaction occurring on the cell surface. In chapter 4, we focus on the kinetics of protein interaction on bilayer surface and we also attempt to visualize these interactions by exploring fluorescence microscopy. A self-assembled cell membrane is consisted of various lipids, which cluster themselves in their preferred phase separated regions. Lipid clusters are very important for lipid specific protein interactions. We investigated protein binding on such phase separated regions under a fluorescence microscope. Furthermore, we enzymatically catalyzed proteins, which were covalently bonded on the bilayer surface. This catalytic reaction was monitored both spectroscopically and under a fluorescence microscope. These studies were performed to help us in the better understanding of biological interactions at cell surface. Chapter 5, describes the encapsulation and controlled delivery of antimicrobial compounds from liposomes. Use of antimicrobial coatings on food packaging is one of the important technologies of active packaging for improving food safety. There is growing demand for natural antimicrobials because of fear of adverse health effects of synthetic preservatives. The main objective of this study is to compare antimicrobial activity of free versus encapsulated curcumin. Glass surfaces coated with nano-encapsulated curcumin may be used as an active packaging material in preserving liquid foods; however, further study is required to improve antimicrobial activities of polylactic acid PLA surfaces. In chapter 6, we investigate interactions between receptors and ligands at bilayer surface of polydiacetylene (PDA) liposomal nanoparticles using changes in electronic absorption spectroscopy and fluorescence resonance energy transfer (FRET). We study the effect of mode of linkage (covalent versus noncovalent) between the receptor and liposome bilayer. We also examine the effect of size-dependent interactions between liposome and analyte through electronic absorption and FRET responses. Glucose (receptor) molecules were either covalently or noncovalently attached at the bilayer of nanoparticles, and they provided selectivity for molecular interactions between glucose and glycoprotein ligands of E. coli. These interactions induced stress on conjugated PDA chain which resulted in changes (blue to red) in the absorption spectrum of PDA. The changes in electronic absorbance also led to changes in FRET efficiency between conjugated PDA chains (acceptor) and fluorophores (Sulphorhodamine-101) (donor) attached to the bilayer surface. Interestingly, we did not find significant differences in UV−Vis and FRET responses for covalently and noncovalently bound glucose to liposomes following their interactions with E. coli. We attributed these results to close proximity of glucose receptor molecules to the liposome bilayer surface such that induced stress were similar in both the cases. We also found that PDA emission from direct excitation mechanism was ∼2−10 times larger than that of the FRET-based response. These differences in emission signals were attributed to three major reasons: nonspecific interactions between E. coli and liposomes, size differences between analyte and liposomes, and a much higher PDA concentration with respect to sulforhodamine (SR-101). We have proposed a model to explain our experimental observations. Our fundamental studies reported here will help in enhancing our knowledge regarding interactions involved between soft particles at molecular levels. In chapter 7, we conclude the summary of all work carried out in previous chapters.
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Adhikari, Shishir Raj. "STATISTICAL PHYSICS OF CELL ADHESION COMPLEXES AND MACHINE LEARNING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1562167640484477.
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Shabajee, Preety. "Contribution a l'identification des ligands endogènes de deux récepteurs couplés aux protéines G d'intérêt thérapeutique et d'un site de liaison à la mélatonine. MTx, a new melatonin binding site in sheep brain : discovery, characterization and molecular pharmacology." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR131.
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Mes travaux de thèse ont porté sur la désorphanisation de deux récepteurs couplés aux protéines G (RCPG) et sur la caractérisation d’un nouveau site de liaison à la mélatonine (MLT), nommé MTx. Les RCPG représentent la plus grande famille de protéines transmembranaires et sont des cibles privilégiées de traitements pharmaceutiques car ces récepteurs sont impliqués dans de nombreux processus physiologiques et physiopathologiques. Au sein de cette famille, il existe de nombreuxrécepteurs pour lesquels le ligand n’a pas encore été identifié et sont, de ce fait, appelés RCPG orphelins. Nous nous sommes intéressés à deux d’entre eux ayant un intérêt thérapeutique, le GPR88, impliqué dans la schizophrénie et le GPR21, impliqué dans le diabète de type 2. Au cours de cette thèse, nous avons tenté d’identifier les ligands endogènes de ces deux récepteurs.Au cours de notre campagne de désorphanisation du GPR88 nous avons testé l’activité de plusieurs fluides biologiques au cours de tests fonctionnels par mesure de la concentration d’AMPc dans une lignée cellulaire exprimant de façon stable le récepteur et par une technologie ≪ label-free ≫, l’EPIC. Ces expériences nous ont permis de mettre en évidence une activité agoniste spécifique du liquide céphalo-spinal (LCS). Les lots de LCS actifs ont ensuite été fractionnés selon des gradients de poids moléculaire (PM), mettant en évidence une activité agoniste spécifique dans la fraction de plus petite taille, inférieure à 3 kDa. Le fractionnement successif en HPLC phase inverse de cette ≪ fraction < 3 kDa ≫, a mis en évidence de nouvelles fractions actives spécifiques dans les premières eluees, suggérant une molécule plutôt polaire. La dernière fraction active a ensuite été analysée par spectrométrie de masse (MS) à haute résolution afin d’identifier les molécules contenues. La MSnous a permis d’identifier clairement deux entités chimiques, la créatine et l’hypoxanthine, et une troisième pour laquelle nous n’avons pas de formule chimique précise, mais un PM d’environ 175 Da. Une étude approfondie des bases de données des métabolites présents dans le LCS nous a permis d’identifier 10 composés candidats d’environ 175 Da à considérer en plus de la créatine et de l’hypoxanthine. Ces douze composés ont été testés individuellement ou combinés dans le test de mesure d’AMPc sans qu’aucune activité agoniste n’ait pu être identifiée. Ces études nous permettent de conclure que le ligand du récepteur GPR88 est contenu dans le LCS, a un PM inférieur à 3 kDa, est très polaire, ce qui nous permet de rejeter les lipides et les acides gras. Nous pouvons également exclure les petites molécules testées de la liste de ligands potentiels, sans pour autant rejeter leurs énantiomères non commercialement disponibles. D’autres techniques de séparation/fractionnement(par exemple une chromatographie HILIC) et une réduction des délais entre les fractionnements et les tests fonctionnels garantissant une meilleure stabilité de la molécule, nous permettront certainement d’identifier le ligand du GPR88G-protein coupled receptors (GPCR) are the largest transmembrane protein family of the genome.Although, they are involved in numerous physiological processes, there are still some receptors among this family for which no ligand has been identified yet. These are called orphan receptors. We focused on two of these orphan receptors: GPR88 and GPR21, showing therapeutic potential in schizophrenia and diabetes mellitus, respectively. During this PhD thesis, we aimed to identify the ligands of these receptors using functional assays and by screening endogenous compounds libraries. Our approaches allowed us to identify the cerebro-spinal fluid (CSF) as a source for the GPR88 receptor ligand. This molecule appears to be very polar with a molecular weight below 3kDa . We also ruled out some compounds contained in the CSF, that we identified in active fractions by mass spectrometry. Concerning GPR21, the assays developped in our laboratory did not permit to detect any specific activity in the libraries nor in the tested biological fluids. In a second part of this PhD program, we pharmacologically characterized a new melatonin (MLT) binding site, named MTx. This site was discovered through autoradiography experiments, with high radiolabelled doses of MLT. MLT is a hormone, mainly synthesized at night by the pineal gland. It is involved in numerous physiological processes and in regulating circadian and circannual rhythms. The identification of this new site, as well as deciphering its roles, might allow us to enrich our knowledge on MLT, and to understand the mode of action of some treatments involving melatoninergic compounds. This site has a pharmacological profile unprecedently described. It can bind both MLT and serotonin, which is not the case with classical melatoninergic nor serotoninergic receptors. Our objectives for the work on MTx, was to identify the gene/protein responsible for the MLT binding and subsequently perform functional studies to further characterize this protein
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Alves, Ariane Ferreira Nunes. "Simulações computacionais de desenovelamento de proteína e complexação de ligantes com amostragem aumentada." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/46/46131/tde-14122017-135400/.
Full textAbstract:
Simulações moleculares podem fornecer informações e detalhes mecanísticos que são difíceis de obter de experimentos. No entanto, fenômenos bioquímicos como formação de complexos proteína-ligante e desenovelamento de proteína são lentos e difíceis de amostrar na escala de tempo geralmente atingida por simulações de dinâmica molecular (MD) convencionais. Esses fenômenos moleculares foram estudados aqui pela combinação de simulações de MD com diversos métodos e aproximações para aumentar a amostragem configuracional: método de energia de interação linear (LIE), a aproximação de ensemble ponderado (WE) e dinâmica molecular dirigida (SMD). Uma equação foi parametrizada para prever afinidades entre pequenas moléculas e proteínas baseada na aproximação LIE, que foca a amostragem computacional nos estados complexado e não-complexado do ligante. A flexibilidade proteica foi introduzida usando ensembles de configurações obtidos de simulações de MD. Diferentes esquemas de média foram testados para obter afinidades totais de complexos proteína-ligante, revelando que muitas configurações de complexo contribuem para as afinidades de proteínas flexíveis, enquanto as afinidades de proteínas rígidas são dominadas por uma configuração de complexo. O mutante L99A da lisozima T4 (T4L) é provavelmente a proteína mais frequentemente usada para estudar complexação de ligantes. Estruturas cristalográficas mostram que a cavidade de ligação artificial criada pela mutação é pouco acessível, portanto movimentos proteicos ou uma respiração conformacional são necessários para permitir a entrada e saída de ligantes. Simulações de MD foram combinadas aqui com a aproximação de WE para aumentar a amostragem de eventos infrequentes de saída do benzeno de T4L. Quatro possíveis caminhos foram encontrados e movimentações de alfa-hélices e cadeias laterais envolvidas na saída do ligante foram caracterizadas. Os quatro caminhos correspondem a túneis da proteína previamente observados em simulações de MD longas de T4L apo, sugerindo que a heterogeneidade de caminhos ao longo de túneis intrínsecos é explorada por pequenas moléculas para sair de cavidades de ligação enterradas em proteínas. Experimentos de microscopia de força atômica revelaram informações detalhadas do desenovelamento forçado e da estabilidade mecânica da rubredoxina, uma proteína ferro-enxofre simples. O desenovelamento completo da rubredoxina envolve a ruptura de ligações covalentes. Portanto, o processo de desenovelamento foi simulado aqui por simulações de SMD acopladas a uma descrição clássica da dissociação de ligações. A amostragem de eventos de desenovelamento forçado foi aumentada pelo uso de velocidades rápidas de esticamento. Os resultados foram analisados usando um modelo teórico válido para regimes de desenovelamento forçado lentos e rápidos. As simulações revelaram que mudanças no ponto de aplicação de força ao longo da sequência da rubredoxina levam a diferentes mecanismos de desenovelamento, caracterizados por variáveis graus de rompimento de ligações de hidrogênio e estrutura secundária da proteína.Molecular simulations may provide information and mechanistic insights that are difficult to obtain from experiments. However, biochemical phenomena such as ligand-protein binding and protein unfolding are slow and hard to sample on the timescales usually reached by conventional molecular dynamics (MD) simulations. These molecular phenomena were studied here by combining MD simulations with several methods or approximations to enhance configurational sampling: linear interaction energy (LIE) method, weighted ensemble (WE) approach and steered molecular dynamics (SMD). An equation was parametrized to predict affinities between small molecules and proteins based on the LIE approximation, which focus computational sampling in ligand bound and unbound states. Protein flexibility was introduced by using ensembles of configurations obtained from MD simulations. Different averaging schemes were tested to obtain overall affinities for ligand-protein complexes, revealing that many bound configurations contribute to affinities for flexible proteins, while affinities for rigid proteins are dominated by one bound configuration. T4 lysozyme (T4L) L99A mutant is probably the protein most often used to study ligand binding. Crystal structures show the artificial binding cavity created by the mutation has low accessibility, so protein movements or conformational breathing are necessary to allow the entry and egress of ligands. MD simulations were combined here with the WE approach to enhance sampling of infrequent benzene unbinding events from T4L. Four possible pathways were found and motions on alpha-helices and side chains involved in ligand egress were characterized. The four pathways correspond to protein tunnels previously observed in long MD simulations of apo T4L, suggesting that pathway heterogeneity along intrinsic tunnels is explored by small molecules to egress from binding cavities buried in proteins. Previous atomic force microscopy experiments revealed detailed information on the forced unfolding and mechanical stability of rubredoxin, a simple iron-sulfur protein. Complete unfolding of rubredoxin involves rupture of covalent bonds. Thus, the unfolding process was simulated here by SMD simulations coupled to a classical description of bond dissociation. Sampling of forced unfolding events was increased by using fast pulling velocities. Results were analyzed using a theoretical model valid for both slow and fast forced unfolding regimes. Simulations revealed that changing the points of force application along the rubredoxin sequence leads to different unfolding mechanisms, characterized by variable degrees of disruption of hydrogen bonds and secondary protein structure.
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Hüfner, Tobias [Verfasser], and Gerhard [Akademischer Betreuer] Klebe. "Expanding the Toolbox for Computational Analysis in Rational Drug Discovery: Using Biomolecular Solvation to Predict Thermodynamic, Kinetic and Structural Properties of Protein-Ligand Complexes / Tobias Hüfner ; Betreuer: Gerhard Klebe." Marburg : Philipps-Universität Marburg, 2019. http://d-nb.info/1211086305/34.
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Brimau, Fanny. "Rôle des odorants-binding protein dans le mécanisme de transduction olfactive : implication de modifications post-traductionnelles dynamiques dans la spécificité de liaison avec les ligands." Thesis, Tours, 2010. http://www.theses.fr/2010TOUR4038/document.
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Les OBP sont des petites protéines solubles qui se lient avec des molécules odorantes et phéromonales. Le rôle des OBPs n’est pas complètement compris. Une hypothèse suggère que l’OBP solubilise et transporte les ligands aux récepteurs olfactifs et la liaison entre les molécules odorantes et l’OBP est non spécifique. Une autre hypothèse suggère que le complexe formé est une liaison spécifique entre une molécule odorante donnée et une OBP spécifique. Ce travail de thèse montre que les OBPs sont impliquées dans la première étape de la discrimination des odeurs. Dans un premier temps, nous avons montré l’implication de la Phe35 et la Tyr 82 dans la sortie du ligand par l’OBP. Dans un second temps, nous avons mis en évidence la présence de différentes isoformes d’OBP et de VEG qui diffèrent par les modifications post-traductionnelles (phosphorylation et GlcNAcylation) a la fois sur les protéines natives extraites de la muqueuse respiratoire et sur les protéines recombinantes produites par P.pastoris et CHO. Ces isoformes sont capables de discriminer des molécules odorantes et phéromonales. Les OBPs ne sont pas des transporteurs passifs car elles assurent un fin codage des molécules odorantes ou phéromonales avant l’interaction de ce complexe avec un récepteur spécifiqueOBPs are small soluble proteins that bind with odorant molecules and pheromones. The role of OBP is not completely understood. A hypothesis suggests that OBP solubilize and transport the ligands to olfactory receptors and the binding between odorant molecule and OBP is unspecific. An other hypothesis suggest that the complex formed is the specific binding between a given odorant molecule and a specific OBP. This work of thesis show that OBP are involved in the first step of odorant discrimination. Initially, we have showed the involvement of the Phe35 and Tyr 82 in the uptake of ligands by OBP. Second, we have given rise to the presence of various isoform of OBP and VEG that differ by post-translational modifications (phosphorylation and GlcNAcylation) both on natives proteins extract of respiratory mucosa and on recombinants proteins produce by P. pastoris and CHO. These isoforms are able to discriminate of odorant molecules and pheromones. OBPs are not passives carriers because they ensure a fine coding of odorant molecules and pheromones before interaction of this complex with specific receptor
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Ousley, Amanda. "Engineering the human vitamin D receptor to bind a novel small molecule: investigating the structure-function relationship between human vitamin d receptor and various ligands." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39580.
Full textAbstract:
The human vitamin D receptor (hVDR) is a member of the nuclear receptor superfamily, involved in calcium and phosphate homeostasis; hence implicated in a number of diseases, such as Rickets and Osteoporosis. This receptor binds 1α,25-dihydroxyvitamin D3 (also referred to as 1,25(OH)2D3) and other known ligands, such as lithocholic acid. Specific interactions between the receptor and ligand are crucial for the function and activation of this receptor, as implied by the single point mutation, H305Q, causing symptoms of Type II Rickets. In this work, further understanding of the significant and essential interactions between the ligand and the receptor were deciphered, through a combination of rational and random mutagenesis. A hVDR mutant, H305F, was engineered with increased sensitivity towards lithocholic acid, with an EC50 value of 10 µM and 40 + 14 fold activation in mammalian cell assays, while maintaining wild-type activity with 1,25(OH)2D3. Furthermore, via random mutagenesis, a hVDR mutant, H305F/H397Y, was discovered to bind a novel small molecule, cholecalciferol, a precursor in the 1α,25-dihydroxyvitamin D3 biosynthetic pathway, which does not activate wild-type hVDR. This variant, H305F/H397Y, binds and activates in response to cholecalciferol concentrations as low as 100 nM, with an EC50 value of 300 nM and 70 + 11 fold activation in mammalian cell assays.
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Benkestock, Kurt. "Electrospray Ionization Mass Spectrometry for Determination of Noncovalent Interactions in Drug Discovery." Doctoral thesis, KTH, Analytisk kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4730.
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Noncovalent interactions are involved in many biological processes in which biomolecules bind specifically and reversibly to a partner. Often, proteins do not have a biological activity without the presence of a partner, a ligand. Biological signals are produced when proteins interact with other proteins, peptides, oligonucleotides, nucleic acids, lipids, metal ions, polysaccharides or small organic molecules. Some key steps in the drug discovery process are based on noncovalent interactions. We have focused our research on the steps involving ligand screening, competitive binding and ‘off-target’ binding. The first paper in this thesis investigated the complicated electrospray ionization process with regards to noncovalent complexes. We have proposed a model that may explain how the equilibrium between a protein and ligand changes during the droplet evaporation/ionization process. The second paper describes an evaluation of an automated chip-based nano-ESI platform for ligand screening. The technique was compared with a previously reported method based on nuclear magnetic resonance (NMR), and excellent correlation was obtained between the results obtained with the two methods. As a general conclusion we believe that the automated nano-ESI/MS should have a great potential to serve as a complementary screening method to conventional HTS. Alternatively, it could be used as a first screening method in an early phase of drug development programs when only small amounts of purified targets are available. In the third article, the advantage of using on-line microdialysis as a tool for enhanced resolution and sensitivity during detection of noncovalent interactions and competitive binding studies by ESI-MS was demonstrated. The microdialysis device was improved and a new approach for competitive binding studies was developed. The last article in the thesis reports studies of noncovalent interactions by means of nanoelectrospray ionization mass spectrometry (nanoESI-MS) for determination of the specific binding of selected drug candidates to HSA. Two drug candidates and two known binders to HSA were analyzed using a competitive approach. The drugs were incubated with the target protein followed by addition of site-specific probes, one at a time. The drug candidates showed predominant affinity to site I (warfarin site). Naproxen and glyburide showed affinity to both sites I and II.QC 20100705
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Grimsley, Philip George Medical Sciences Faculty of Medicine UNSW. "Receptor mediated catabolism of plasminogen activators." Awarded By:University of New South Wales. Medical Sciences, 2009. http://handle.unsw.edu.au/1959.4/44489.
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Humans have two plasminogen activators (PAs), tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA), which generate plasmin to breakdown fibrin and other barriers to cell migration. Both PAs are used as pharmaceuticals but their efficacies are limited by their rapid clearance from the circulation, predominantly by parenchymal cells of the liver. At the commencement of the work presented here, the hepatic receptors responsible for mediating the catabolism of the PAs were little understood. tPA degradation by hepatic cell lines was known to depend on the formation of binary complexes with the major PA inhibitor, plasminogen activator inhibitor type-1 (PAI-1). Initial studies presented here established that uPA was catabolised in a fashion similar to tPA by the hepatoma cell line, HepG2. Other laboratories around this time found that the major receptor mediating the binding and endocytosis of the PAs is Low Density Lipoprotein Receptor-related Protein (LRP1). LRP1 is a giant 600 kDa protein that binds a range of structurally and functionally diverse ligands including, activated α2 macroglobulin, apolipoproteins, β amyloid precursor protein, and a number of serpin-enzymes complexes, including PA??PAI-1 complexes. Further studies for the work presented here centred on this receptor. By using radiolabelled binding assays, ligand blots, and Western blots on cultured cells, the major findings are that: (1) basal LRP1 expression on HepG2 is low compared to a clone termed, HepG2a16, but appears to increase in long term culture; (2) a soluble form of LRP1, which retains ligand-binding capacity, is present in human circulation; (3) soluble LRP1 is also present in cerebral spinal fluid where its role in neurological disorders such as Alzheimer??s disease is a developing area of interest; and (4) the release of LRP1 is a mechanism conserved in evolution, possibly as distantly as molluscs. The discovery, identification, and characterisation of soluble LRP1 introduces this protein in the human circulation, and presents a possible further level of regulation for its associated receptor system.