Дисертації з теми "Interactive substrates"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Interactive substrates.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Interactive substrates".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Battut, Alexandre. "Interaction substrates and instruments for interaction histories." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASG026.
Анотація:
Dans le monde numérique comme dans le monde physique, nos interactions avec les objets laissent des traces qui racontent l'histoire qui les a façonnés au fil du temps. Ces données historiques peuvent être consultées par les utilisateurs afin de mieux comprendre les étapes qui ont conduit à l'état actuel de leur système. Elles peuvent également être re-documentées afin d'arranger l'historique d'une manière plus compréhensible pour les utilisateurs. Dans des environnements collaboratifs, les utilisateurs peuvent être amenés à partager ces données, afin de mieux coordonner ou synchroniser leur travail d'équipe.Des travaux antérieurs ont tenté de démontrer les avantages des historiques partagés entre applications, mais les implémentations actu- elles des historiques dans les systèmes interactifs continuent de confiner les historiques à leur application d'origine.Les utilisateurs ne peuvent pas croiser leur historiques pour corréler les événements qui se sont produits dans différentes applications. Dans cette thèse, je montre que concevoir des historiques de l'interaction pouvant être partagés entre les applications et les utilisateurs faciliterait la navigation, la compréhension et la réutilisation des données historiques. J'ancre le début de mes travaux dans le cas de l'écriture collaborative afin d'explorer des écologies de traces et des usages familiers, mais néanmoins complexes. J'identifie les pratiques récurrentes et les problèmes liés à l'utilisation des données historiques en interrogeant des utilisateurs habitués de l'écriture collaborative, et je mène plusieurs activités de conception basées sur les observations qui en découlent. Je décris ensuite un premier système en tant que preuve de concept intégrant deux outils résultant de ces activités de conception. Ce système intègre également la première itération d'une structure unique pour les données d'historique partagées entre applications et utilisateurs. Les résultats des études utilisateurs menées sur ce système montrent que ces derniers expriment effectivement le besoin de disposer d'historiques d'interaction unifiés et personnalisables. En compilant les données recueillies au cours de ces activités de recherche et en me basant sur des travaux antérieurs concernant les "médias dynamiques partageables" et les substrats d'interaction, je décris un cadre permettant de concevoir des historiques d'interaction plus flexibles. Je présente Steps, une structure d'unification des données historiques qui intègre un noyau d'attributs descriptifs qui préserve l'intégrité d'une trace entre les applications, et des attributs contextuels extensibles qui permettent aux utilisateurs de modeler leurs historiques en fonction de leurs besoins. Je présente ensuite OneTrace, un prototype basé sur les Steps. Son implémentation suit mon cadre descriptif pour les historiques inter-applications et définit l'historique comme un matériau numérique à façonner par l'utilisation d'outils dédiés. Je discute des opportunités offertes par cette approche pour réaliser un changement de paradigme sur la façon dont nous concevons les historiques et leurs outilsIn the digital world, as in the physical world, our interactions with objects leave traces that tell the story of the actions that shaped these objects over time. This historical data can be accessed by end users to help them better understand the steps that led to the current state of their system. These traces can also be reused for activities such as re-documenting their own history to arrange it in a way that they find more understandable. Users may also be led to share these data in collaborative environments, to better coordinate and synchronize their work. While previous work has attempted to show the benefits of cross-application histories, current implementations of interaction histories in interactive systems tend to tie history data to their source application. This prevents users from cross-referencing historical data to review and correlate events that occurred in different applications.In this thesis, I argue that designing interaction histories that can be shared among applications and users would support browsing, understanding and reusing historical data. I first ground my work in the use case of collaborative writing to explore relatable yet complex traces ecologies and interaction history use. I identify recurring practices and issues with the use of history data by interviewing knowledge workers and conducting several design activities based on these observations. I describe a first proof-of-concept system integrating two history instruments resulting from these design activities, and the first iteration of a unifying structure for historical data to be shared among applications and users. The results of user studies show that users indeed express a need for unified and customizable interaction histories.Compiling the data gathered during these research activities and based on previous works about “Dynamic Shareable Media” and the Interaction Substrates and Instruments model, I describe a framework to help create more flexible interaction histories. The goal is to describe how to design interaction history systems that would help users take control of their historical data. I introduce Steps, a structure for unifying historical data that includes descriptive core attributes to preserve the integrity of a trace across applications, and extensible contextual attributes that let users reshape their histories to suit their needs. I then introduce OneTrace, a proof-of-concept prototype based on Steps that follows my descriptive framework for cross-application histories and defines interaction histories as digital material to be shaped by digital tool use. I discuss the opportunities offered by this approach to support a shift in paradigm on how we design and interact with interaction histories
2
Gulick, Danielle. "An Examination of the Neural Substrates Underlying the Dissociable and Interactive Effects of Acute Ethanol and Nicotine on Learning, Anxiety, and Locomotion in Fear Conditioning and the Plus Maze Discriminative Avoidance Task." Diss., Temple University Libraries, 2008. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/18921.
Анотація:
PsychologyPh.D.
Studies have demonstrated dissociable effects of nicotine alone versus in combination with ethanol on learning, and these effects may depend on different neural substrates. Furthermore, the effects of nicotine in different brain areas may produce other behavioral changes - such as changes in anxiety - that alter learning. This research examines the interactive effects of ethanol and nicotine on learning, anxiety, and locomotion, and the dissociation of these effects by brain area. Specifically, we examine the interactive effects of systemic ethanol with nicotine infusion into the dorsal hippocampus, ventral hippocampus, or anterior cingulate on contextual and cued fear conditioning and the plus-maze discriminative avoidance task (PMDAT). In addition, we use dihydro-beta-erythroidine (DHbetaE), a nicotinic receptor antagonist, to examine the involvement of acetylcholingeric nicotinic receptors (nAChRs) in the effects of ethanol alone and in the mediation of ethanol-induced changes by nicotine. In the PMDAT, we examine whether caffeine produces the same effects as nicotine in the PMDAT. In fear conditioning, nicotine acts in the dorsal hippocampus to enhance contextual fear conditioning and in the anterior cingulate to reverse ethanol-induced contextual and cued fear conditioning deficits through inactivation of high-affinity beta2 subunit-containing nAChRs. In the PMDAT, ethanol produces learning deficits, anxiolysis, and increased locomotion, and nicotine reverses the effects of ethanol. Although caffeine and ethanol interact to modulate behavior in the PMDAT, caffeine fails to reverse ethanol-induced learning deficits. Finally, the effects of nicotine and ethanol, both alone and in combination, on learning, anxiety, and locomotion depend on distinct neural substrates. Nicotine acts in the anterior cingulate to reverse ethanol-induced learning deficits but produces diverse effects on anxiety that vary across all three brain areas.
Temple University--Theses
3
Rahman, Nahid 1974. "Polypyrrole : an interactive substrate for bone regeneration." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50554.
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1998.Includes bibliographical references (leaves 59-68).
Current methods of bone repair rely on autografts (bone from a donor site) and allografts (bone from human cadaver). However, these methods are plagued with disadvantages. There is a clear and urgent need to provide alternatives for regenerating and repairing bone. Bone is known to be one of the many connective tissues in the body that are responsive to exogenous electrical stimulation. Based on this principle, this thesis explores the potential of using an electrically conducting polymer, polypyrrole, as a substrate for bone regeneration. Optically transparent thin films of polypyrrole, with a polyanionic dopant, poly(styrenesulfonate), were synthesized electrochemically and characterized by X-Ray Photoelectron Spectroscopy, UV/VIS spectroscopy, Scanning Electron Microscopy and by electrical conductivity measurements. In this study, Bone Marrow Stromal Cells (BMSC), which are the progenitor cells to bone cells (osteoblasts), were used as the in vitro model system. Their viability, proliferation and differentiation capabilities were evaluated on polypyrrole, in the absence and presence of electrical stimulation. Results indicate that polypyrrole is ideally suited as a substratum for BMSC growth and differentiation. The application of an electrical stimulus through the polypyrrole substrate was found to induce the differentiation of BMSC towards an osteogenic lineage. Thus, polypyrrole, by virtue of its conductive properties, its in vitro biocompatibility and its flexibility in altering surface characteristics, has an exciting potential as a suitable interactive substrate for bone regeneration.
by Nahid Rahman.
S.M.
4
Rahman, Nahid S. M. Massachusetts Institute of Technology. "Polypyrrole : an interactive substrate for bone regeneration." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50554.
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1998.Includes bibliographical references (leaves 59-68).
Current methods of bone repair rely on autografts (bone from a donor site) and allografts (bone from human cadaver). However, these methods are plagued with disadvantages. There is a clear and urgent need to provide alternatives for regenerating and repairing bone. Bone is known to be one of the many connective tissues in the body that are responsive to exogenous electrical stimulation. Based on this principle, this thesis explores the potential of using an electrically conducting polymer, polypyrrole, as a substrate for bone regeneration. Optically transparent thin films of polypyrrole, with a polyanionic dopant, poly(styrenesulfonate), were synthesized electrochemically and characterized by X-Ray Photoelectron Spectroscopy, UV/VIS spectroscopy, Scanning Electron Microscopy and by electrical conductivity measurements. In this study, Bone Marrow Stromal Cells (BMSC), which are the progenitor cells to bone cells (osteoblasts), were used as the in vitro model system. Their viability, proliferation and differentiation capabilities were evaluated on polypyrrole, in the absence and presence of electrical stimulation. Results indicate that polypyrrole is ideally suited as a substratum for BMSC growth and differentiation. The application of an electrical stimulus through the polypyrrole substrate was found to induce the differentiation of BMSC towards an osteogenic lineage. Thus, polypyrrole, by virtue of its conductive properties, its in vitro biocompatibility and its flexibility in altering surface characteristics, has an exciting potential as a suitable interactive substrate for bone regeneration.
by Nahid Rahman.
S.M.
5
Arjmandi-Tash, Omid. "Interaction of droplets and foams with solid/porous substrates." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24889.
Анотація:
Current problems on the interaction of complex liquids (i.e. droplets or foams) with complex surfaces (i.e. soft deformable or porous surfaces) are addressed in the following areas: (1) wetting of deformable substrates and surface forces, (2) kinetics of wetting and spreading of non-Newtonian liquids over porous substrates, (3) kinetics of spreading of non-Newtonian solutions over hair, (4) free drainage of foams produced from non-Newtonian solutions, and (5) foam drainage placed on porous substrates. Equilibrium of liquid droplets on deformable substrates was investigated and the effect of disjoining pressure action in the vicinity of the apparent three phase contact line was taken into account. It was proven that the deformation of soft solids is determined by the action of surface forces inside the transition zone. Spreading/imbibition of blood, which is a power law shear thinning non-Newtonian liquid, over a dry porous layer was investigated from both theoretical and experimental points of view. It was found that blood droplet spreading/imbibition over porous substrates shows two different behaviours: (i) partial wetting case with three subsequent stages: initial fast spreading, constant maximum droplet base and the shrinkage of the droplet base; (ii) complete wetting case with only two stages: initial fast spreading and the shrinkage of the droplet base. The wetting of hair tresses by aqueous solutions of two commercially available polymers, AculynTM 22 (A22) and AculynTM 33 (A33) was investigated experimentally. Both A22 and A33 solutions demonstrate well pronounced shear thinning behaviour. Initial contact angle of the A22 and A33 solutions on hair tresses was about 100o. The A22 droplets remained on the hair tress after spreading for at least half an hour. However, a fast penetration of the A33 droplets inside the hair tresses was observed when advancing contact angle in the course of spreading reached a critical value of about 60o. This could be explained by Cassie-Wenzel wetting transition which is caused by filling the pores inside the porous media by liquid. The influence of non-Newtonian rheology of A22 and A33 solutions on foam drainage was also investigated experimentally and a new theory of foam drainage was presented for the case of free drainage. For lowly viscous polymeric solutions and under the assumption of rigid surface of the Plateau border, the predicted values of the time evolution of the foam height and liquid content were in good agreement with the experimental data. However, in the case of highly viscous solutions an interfacial mobility at the surface of the Plateau border has to be taken into account. A completely new theory of foam drainage placed on porous substrate was developed. It was found that there are three different regimes of the process: (i) a rapid imbibition, the imbibition into the porous substrate dominates as compared with the foam drainage; (ii) an intermediate imbibition, that is, the imbibition into the porous substrate and the rate of drainage are comparable; (iii) a slow imbibition, the rate of drainage inside the foam is higher than the imbibition into the porous substrate for a period of time and a free liquid layer is formed over the porous substrate.
6
Hill, S. D. "Plasma torch interaction with a melting substrate." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17261.
7
Zhang, Baoshe. "A study of substrate--liquid crystal interaction /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202003%20ZHANG.
Анотація:
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 176-186). Also available in electronic version. Access restricted to campus users.
8
Kinstrie, Ross Stuart. "Identification of Drosophila DYRK family substrates and interacting proteins." Thesis, University of Glasgow, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433084.
9
Riley, Jane. "The interaction of topoisomerase IV with potential DNA substrates." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272768.
10
Zhang, Xinchen. "Interaction of PEG-ylated Lipid Nanoparticles with Silica Substrates." Thesis, Uppsala universitet, Institutionen för kemi - BMC, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-296349.
Анотація:
In this project, the interaction between polyethylene glycol modified (PEG-ylated) lipid nanoparticles and silica substrates was studied to find out how this interaction was affected by bulk concentration, temperature and the composition of particles. One kind of lipodisk and four kinds of PEG-ylated liposome were prepared from lipid films and characterized by quartz crystal microbalance with dissipation monitoring (QCM-D) instrument mounted with silica sensor. The detailed information of particle-silica interaction could be obtained from the raw data, frequency and dissipation values, and the adsorbed mass surface density calculated from the raw data. Lipodisks could be immobilized on the silica surface. Whether they would be rinsed away by PBS buffer was influenced by both the bulk concentration and temperature. The way of their binding could change and the changing process was affected by temperature. PEG-ylated liposomes could also be immobilized on the silica surface, and they could break and spread to form supported lipid bilayer in certain conditions, for example, the changing of temperature or the using of certain lipids. Supported lipid bilayers were created with high reproducibility in this project, which could be very useful to the future study of transmembrane proteins functions and lipodisk properties.
11
Richter, Andreas. "Structure formation and fractionation in systems of colloidal rods." Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2007/1309/.
12
Markevich, Alexander. "Modification of electronic properties of graphene by interaction with substrates and dopants." Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/10726.
Анотація:
First-principles calculations have been carried out to investigate structural and electronic properties of graphene on SiC and diamond substrates and for a study of doping of fluorographene with various surface adsorbates. New insight is given into the problem of the decoupling of the graphene layers from SiC substrates after epitaxial growth. Mechanisms of hydrogen penetration between graphene and SiC(0001) surface, and properties of hydrogen and fluorine intercalated structures have been studied. Energy barriers for diffusion of atomic and molecular hydrogen through the interface graphene layer with no defects and graphene layers containing Stone-Wales defect or two- and four-vacancy clusters have been calculated. It is argued that diffusion of hydrogen towards the SiC surface occurs through the hollow defects in the interface graphene layer. It is further shown that hydrogen easily migrates between the graphene layer and the SiC substrate and passivates the surface Si bonds, thus causing the graphene layer decoupling. According to the band structure calculations the graphene layer decoupled from the SiC(0001) surface by hydrogen intercalation is undoped, while that obtained by the fluorine intercalation is p-type doped. Further, structure and the electronic properties of single and double layer graphene on H-, OH-, and F- passivated (111) diamond surface have been studied. It is shown that graphene only weakly interacts with the underlying substrates and the linear dispersion of graphene pi-bands is preserved. For graphene on the hydrogenated diamond surfaces the charge transfer results in n-type doping of graphene layers and the splitting of conduction and valence bands in bilayer graphene. For the F- and OH-terminated surfaces, charge transfer and doping of graphene do not occur. Finally, the possibility of doping fluorographene by surface adsorbates have been investigated. The structure and electronic properties of fluorographene with adsorbed K, Li, Au atoms, and F4-TCNQ molecule are described. It is shown that adsorption of K or Li atoms results in electron doping of fluorographene, while Au atoms and F4-TCNQ introduce deep levels inside the band gap. The calculated value of the fluorographene work function is extremely high, 7.3 eV, suggesting that p-type doping is difficult to achieve.
13
Yap, Jessica. "Identification of Plasmodium falciparum protein kinase substrates and interacting proteins." Honors in the Major Thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/644.
Анотація:
Characterization of PfPKA and PfPK5 substrates, as well as the proteins they interact with, will help us to develop innovative therapies targeting binding sites.; Malaria is a devastating disease that results in almost one million deaths annually. Most of the victims are children under the age of five in Sub-Saharan Africa. Malaria parasite strains throughout developing countries are continually building resistance to available drugs. Current therapies such as mefloquine, chloroquine, as well as artemisinin are becoming less effective, and this underscores the urgency for therapeutics directed against novel drug targets. In order to identify new drug targets, the molecular biology of the malaria parasite Plasmodium needs to be elucidated. Plasmodium exhibits a unique cell cycle in which it undergoes multiple rounds of DNA synthesis and mitosis without cytokinesis. Thus, cell cycle regulatory proteins are likely to be promising pathogen-specific drug targets. It is expected that fluctuating activity of key proteins, such as protein kinases, play an essential role in regulating the noncanonical life cycle of Plasmodium. Consequently, malarial kinases are a prime target for therapy. One way to better understand the role of malarial kinases in Plasmodium cell cycle regulation is to identify putative protein kinase substrates and interacting proteins. Two malarial kinases that have been implicated in regulating malaria parasite cell cycle stages were investigated in this study: P. falciparum CDK-like Protein Kinase 5 (PfPK5) and cAMP-Dependent Protein Kinase A (PfPKA). A transgenic P. falciparum line was created for the expression of epitope-tagged PfPK5 for pull-down analysis. Phospho-substrate antibodies were used to identify physiological substrates of both PfPK5 and PfPKA. Immunoblotting with these antibodies identified several potential substrates. Identities of the PfPKA physiological substrates were determined from the global P. falciparum phosphoproteome dataset that has recently been generated in our laboratory.B.S.
Bachelors
Burnett School of Biomedical Sciences
Molecular and Microbiology
14
Panse, Vikram G. "Interaction Of Chaperone SecB With Protein Substrates: A Biophysical Study." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/242.
Анотація:
In the cell, as in in vitro, the final conformation of a protein is determined by it's amino acid sequence (1). Some isolated proteins can be denatured and refolded in vitro in absence of extrinsic factors. However, in order to fold in the cell, the newly synthesized polypeptide chain has to negotiate an environment far more complex than that faced by the unfolded chain in vitro. Cells have evolved proteins called “chaperones” to assist folding and assembly of polypeptides (2). Thus, the linear sequence of a protein not only contains information that specifies the final three-dimensional functional form, but also recognition motifs, which can be recognized by the cellular folding machinery.
The work reported in this thesis is aimed at understanding some aspects of recognition of target substrates by the cytosolic chaperone, SecB, which forms part of the protein translocation machinery in E. coli. The sec pathway is involved in both translocation of precursor proteins across and the insertion of integral membrane proteins into the cytoplasmic membrane (3).
Chapter one discusses some general aspects of protein folding and briefly describes chaperone systems, which have been extensively characterized in literature.
Chapter two discusses the effect of chaperone SecB on the refolding pathway of a model substrate protein barstar, whose folding pathway has been extensively characterized (4,5). The effect of SecB on the refolding kinetics of the small protein barstar (wild type) and
fluorescein labeled C82A (single Cys mutant) in 1 M guanidine hydrochloride at pH 7.0 at 25 °C has been investigated using fluorescence spectroscopy. We show that SecB does not bind either the native or the unfolded states of barstar but binds to late near-native intermediate (s) along the folding pathway. ESR studies and fluorescence anisotropy measurements show that SecB forms stable complexes with the near-native intermediate (s). For barstar, polypeptide collapse and formation of a hydrophobic surface are required for binding to SecB. Steady state polarization measurements indicated the presence of stable complexes of barstar bound to SecB. Studies on the spin labeled C82A show an immobilization of the spin label adduct at the 40th position of barstar, suggesting that the binding of SecB to barstar occurs in that region. SecB does not change the apparent rate constant of barstar refolding. The kinetic data for SecB binding to barstar are not consistent with simple kinetic partitioning models (6).
Chapter three discusses the energetics of substrate:SecB interactions using the following model protein substrates: unfolded RNase A, BPTI, partially folded disulfide intermediates of alpha-lactalbumin,. The thermodynamics of binding of unfolded polypeptides to the chaperone SecB were investigated in vitro by isothermal titration calorimetry and fluorescence spectroscopy. The heat capacity changes observed on binding the reduced and carboxamidomethylated forms of alpha-lactalbumin, BPTI, and RNase A were found to be -0.10, -0.29 and -0.41 kcal mol-1 K-1 respectively and suggest that between 7 and 29 residues are buried upon substrate binding to SecB. In all cases binding occurs with a stoichiometry of one polypeptide chain per monomer of SecB. The data are consistent with a model where SecB binds substrate molecules at an exposed hydrophobic cleft (7).
Chapter four discusses the thermodynamics of unfolding to gain insights into the mechanism of assembly and stability of the tetrameric structure. The thermodynamics of unfolding of SecB was studied as a function of protein concentration, by using high sensitivity-differential scanning calorimetry and spectroscopic methods. The thermal unfolding of tetrameric SecB is reversible and can be well described as a two-state transition in which the folded tetramer is converted directly to unfolded monomers. The
value of ACP obtained was 10.7 ± 0.7 kcal mol-1 K-1, which is amongst the highest measured for a multimeric protein. At 298 K, pH 7.4. the AG°U for the SecB tetramer is 27.9 ± 2 kcal mol-1. Denaturant mediated unfolding of SecB was found to be irreversible. The reactivity of the 4 solvent exposed free thiols in tetrameric SecB is salt dependent. The kinetics of reactivity suggests that these four Cysteines are in close proximity to each other and that these residues on each monomer are in chemically identical environments. The thermodynamic data suggest that SecB is a stable, well folded and tightly packed tetramer and that substrate binding occurs at a surface site rather than at an interior cavity (8).
Chapter five discusses the bound state conformation of a model protein substrate of SecB, bovine pancreatic trypsin inhibitor (BPTI), as well as the conformation of SecB itself by using proximity relationships based on site-directed spin-labeling and pyrene fluorescence methods. BPTI is a 58 residue protein and contains 3 disulfide groups between residues 5 and 55, 14 and 38, and 30 and 51. Single disulfide mutants of BPTI were reduced and the free cysteines were labeled with either thiol-specific spin labels or pyrene maleimide. The relative proximity of labeled residues was studied using either electron spin resonance spectroscopy or fluorescence spectroscopy. The data suggest that SecB binds a collapsed coil of reduced unfolded BPTI, which then undergoes a structural rearrangement to a more extended state upon binding to SecB. Binding occurs at multiple sites on the substrate and the binding site on each SecB monomer accommodates less than 21 substrate residues. In addition, we have labeled four, solvent accessible cysteine residues in the SecB tetramer and have investigated their relative spatial arrangement in the presence and absence of the substrate protein. The ESR data suggest that these cysteine residues are in close proximity when no substrate protein is bound, but move away from each other when SecB binds substrate. This is the first direct evidence of a conformational change in SecB upon binding of a substrate protein.
Chapter six discusses the mechanism of dissaggregation of a model peptide aggregate by chaperone SecB. The Hspl04, Hsp70 and Hsp40 chaperone system are capable of dissociating aggregated state(s) of substrate proteins, though little is known of the
mechanism of the process. The interaction of the B chain of insulin with chaperone SecB was investigated using light scattering, pyrene excimer fluorescence and electron spin resonance spectroscopy. We show that SecB prevents aggregation of the B chain of insulin. We show that SecB is capable of dissociating soluble B chain aggregate as monitored by pyrene fluorescence spectroscopy. The kinetics of dissociation of the B chain aggregate by SecB has also been investigated to understand the mechanism of dissociation. The data suggests that SecB does not act as a catalyst in dissociation of the aggregate to individual B chains, rather it binds the small population of free B chains with high affinity, thereby shifting the equilibrium from the ensemble of the aggregate towards the individual B chains. Thus SecB can rescue aggregated, partially folded /misfolded states of target proteins by a thermodynamic coupling mechanism when the free energy of binding to SecB is greater than the stability of the aggregate. Pyrene excimer fluorescence and ESR methods have been used to gain insights on the bound state conformation of the B chain to chaperone SecB. The data suggests that the B chain is bound to SecB in a flexible extended state in a hydrophobic cleft on SecB and that the binding site accommodates approximately 10 residues of substrate (9).
15
Panse, Vikram G. "Interaction Of Chaperone SecB With Protein Substrates: A Biophysical Study." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/242.
Анотація:
In the cell, as in in vitro, the final conformation of a protein is determined by it's amino acid sequence (1). Some isolated proteins can be denatured and refolded in vitro in absence of extrinsic factors. However, in order to fold in the cell, the newly synthesized polypeptide chain has to negotiate an environment far more complex than that faced by the unfolded chain in vitro. Cells have evolved proteins called “chaperones” to assist folding and assembly of polypeptides (2). Thus, the linear sequence of a protein not only contains information that specifies the final three-dimensional functional form, but also recognition motifs, which can be recognized by the cellular folding machinery.
The work reported in this thesis is aimed at understanding some aspects of recognition of target substrates by the cytosolic chaperone, SecB, which forms part of the protein translocation machinery in E. coli. The sec pathway is involved in both translocation of precursor proteins across and the insertion of integral membrane proteins into the cytoplasmic membrane (3).
Chapter one discusses some general aspects of protein folding and briefly describes chaperone systems, which have been extensively characterized in literature.
Chapter two discusses the effect of chaperone SecB on the refolding pathway of a model substrate protein barstar, whose folding pathway has been extensively characterized (4,5). The effect of SecB on the refolding kinetics of the small protein barstar (wild type) and
fluorescein labeled C82A (single Cys mutant) in 1 M guanidine hydrochloride at pH 7.0 at 25 °C has been investigated using fluorescence spectroscopy. We show that SecB does not bind either the native or the unfolded states of barstar but binds to late near-native intermediate (s) along the folding pathway. ESR studies and fluorescence anisotropy measurements show that SecB forms stable complexes with the near-native intermediate (s). For barstar, polypeptide collapse and formation of a hydrophobic surface are required for binding to SecB. Steady state polarization measurements indicated the presence of stable complexes of barstar bound to SecB. Studies on the spin labeled C82A show an immobilization of the spin label adduct at the 40th position of barstar, suggesting that the binding of SecB to barstar occurs in that region. SecB does not change the apparent rate constant of barstar refolding. The kinetic data for SecB binding to barstar are not consistent with simple kinetic partitioning models (6).
Chapter three discusses the energetics of substrate:SecB interactions using the following model protein substrates: unfolded RNase A, BPTI, partially folded disulfide intermediates of alpha-lactalbumin,. The thermodynamics of binding of unfolded polypeptides to the chaperone SecB were investigated in vitro by isothermal titration calorimetry and fluorescence spectroscopy. The heat capacity changes observed on binding the reduced and carboxamidomethylated forms of alpha-lactalbumin, BPTI, and RNase A were found to be -0.10, -0.29 and -0.41 kcal mol-1 K-1 respectively and suggest that between 7 and 29 residues are buried upon substrate binding to SecB. In all cases binding occurs with a stoichiometry of one polypeptide chain per monomer of SecB. The data are consistent with a model where SecB binds substrate molecules at an exposed hydrophobic cleft (7).
Chapter four discusses the thermodynamics of unfolding to gain insights into the mechanism of assembly and stability of the tetrameric structure. The thermodynamics of unfolding of SecB was studied as a function of protein concentration, by using high sensitivity-differential scanning calorimetry and spectroscopic methods. The thermal unfolding of tetrameric SecB is reversible and can be well described as a two-state transition in which the folded tetramer is converted directly to unfolded monomers. The
value of ACP obtained was 10.7 ± 0.7 kcal mol-1 K-1, which is amongst the highest measured for a multimeric protein. At 298 K, pH 7.4. the AG°U for the SecB tetramer is 27.9 ± 2 kcal mol-1. Denaturant mediated unfolding of SecB was found to be irreversible. The reactivity of the 4 solvent exposed free thiols in tetrameric SecB is salt dependent. The kinetics of reactivity suggests that these four Cysteines are in close proximity to each other and that these residues on each monomer are in chemically identical environments. The thermodynamic data suggest that SecB is a stable, well folded and tightly packed tetramer and that substrate binding occurs at a surface site rather than at an interior cavity (8).
Chapter five discusses the bound state conformation of a model protein substrate of SecB, bovine pancreatic trypsin inhibitor (BPTI), as well as the conformation of SecB itself by using proximity relationships based on site-directed spin-labeling and pyrene fluorescence methods. BPTI is a 58 residue protein and contains 3 disulfide groups between residues 5 and 55, 14 and 38, and 30 and 51. Single disulfide mutants of BPTI were reduced and the free cysteines were labeled with either thiol-specific spin labels or pyrene maleimide. The relative proximity of labeled residues was studied using either electron spin resonance spectroscopy or fluorescence spectroscopy. The data suggest that SecB binds a collapsed coil of reduced unfolded BPTI, which then undergoes a structural rearrangement to a more extended state upon binding to SecB. Binding occurs at multiple sites on the substrate and the binding site on each SecB monomer accommodates less than 21 substrate residues. In addition, we have labeled four, solvent accessible cysteine residues in the SecB tetramer and have investigated their relative spatial arrangement in the presence and absence of the substrate protein. The ESR data suggest that these cysteine residues are in close proximity when no substrate protein is bound, but move away from each other when SecB binds substrate. This is the first direct evidence of a conformational change in SecB upon binding of a substrate protein.
Chapter six discusses the mechanism of dissaggregation of a model peptide aggregate by chaperone SecB. The Hspl04, Hsp70 and Hsp40 chaperone system are capable of dissociating aggregated state(s) of substrate proteins, though little is known of the
mechanism of the process. The interaction of the B chain of insulin with chaperone SecB was investigated using light scattering, pyrene excimer fluorescence and electron spin resonance spectroscopy. We show that SecB prevents aggregation of the B chain of insulin. We show that SecB is capable of dissociating soluble B chain aggregate as monitored by pyrene fluorescence spectroscopy. The kinetics of dissociation of the B chain aggregate by SecB has also been investigated to understand the mechanism of dissociation. The data suggests that SecB does not act as a catalyst in dissociation of the aggregate to individual B chains, rather it binds the small population of free B chains with high affinity, thereby shifting the equilibrium from the ensemble of the aggregate towards the individual B chains. Thus SecB can rescue aggregated, partially folded /misfolded states of target proteins by a thermodynamic coupling mechanism when the free energy of binding to SecB is greater than the stability of the aggregate. Pyrene excimer fluorescence and ESR methods have been used to gain insights on the bound state conformation of the B chain to chaperone SecB. The data suggests that the B chain is bound to SecB in a flexible extended state in a hydrophobic cleft on SecB and that the binding site accommodates approximately 10 residues of substrate (9).
16
Reid, K. S. C. "Application of interactive force and energy calculations to enzyme-substrate docking." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47803.
17
Zhen, Juan Reith Maarten E. A. "Interaction between the human dopamine transporter and its substrates and blockers." Normal, Ill. : Illinois State University, 2005. http://proquest.umi.com/pqdweb?index=0&did=1221741311&SrchMode=1&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1177270570&clientId=43838.
Анотація:
Thesis (Ph. D.)--Illinois State University, 2005.Title from title page screen, viewed on April 22, 2007. Dissertation Committee: Maarten E.A. Reith (chair), Hou Tak Cheung, Stephen M. Lasley, Robert L. Preston, Brian J. Wilkinson. Includes bibliographical references and abstract. Also available in print.
18
Yang, Rui. "Interaction between caspases and their substrates in the inflammasome signaling pathway." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1559917811566556.
19
Hodge, Thomas C. "Substrate-film interaction in noble metal/polymer multichip modules." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/10972.
20
Eggenhuisen, Joris Theodoor. "'The interaction between substrate evolution and turbidity current development'." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507691.
21
Molloy, Claire Ann. "Interaction between oestradiol and the IGF-I signal transduction pathway in breast cancer cells." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265214.
22
Xin, Mei. "Interaction of atmospheric elemental mercury with natural, synthetic, and anthropogenically derived substrates." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3289450.
23
Thunström, Filip. "Kinetic Monte-Carlo studies of island shape evolution on weakly-interacting substrates." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150984.
Анотація:
Metal thin films deposited on weakly-interacting substrates constitute an essential element of numerous microelectronic, catalytic, and optical devices. However, the natural tendency of metal atoms to agglomerate, upon condensation on a weakly-interacting surface, in dispersed three-dimensional (3D) islands affects negatively the performance of the above-mentioned devices. The aim of this thesis is to investigate one of the mechanisms governing silver (Ag) 3D island growth on weakly-interacting substrates, i.e. the nucleation of a new layer on the island top. Kinetic Monte Carlo (KMC) simulations are employed to calculate the top island-layer critical radius Rc required for nucleating a new layer in the out-of-plane direction. Single-island simulations are performed for growth temperatures T in the range 250 to 500 K and ratios of the pairwise adatom/substrate atom bond strength EB,sub to the corresponding adatom/adatom value EB,film in the range 0.5 to 0.75. We find that for T values below 250 K the islands exhibit a 2D morphology for all EB,sub/EB,film ratios. In contrast, for T values above 300 K there exists a range of relatively small EB,sub/EB,film values, where 2D morphology dominates. To calculate Rc for each island layer as the island shape evolves, a subroutine is developed and implemented in an existing KMC algorithm. Rc values are computed for 3D island growth at EB,sub/EB,film = 0.5 in the T range 300−500 K and the results show that Rc decreases monotonously from 17.3 to 6.0 Å and saturates approximately at 375 K. This trend is opposite to the typical behavior of islands grown under homoepitaxial conditions, for which the enhancement of downward inter-layer diffusion caused by an increase of T leads to lower atomic densities on the top, i.e. to a lower nucleation probability, and thus to an increase of Rc. This work contributes to the understanding of the physical processes that control thin-film morphological evolution; which is paramount for controlling and manipulating film growth for specific applications.
24
Gervilla, Palomar Víctor. "Metal film growth on weakly-interacting substrates : Stochastic simulations and analytical modelling." Licentiate thesis, Linköpings universitet, Nanodesign, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-154428.
Анотація:
Thin films are nanoscale layers of material, with exotic properties useful in diverse areas, ranging from biomedicine to nanoelectronics and surface protection. Film properties are not only determined by their chemical composition, but also by their microstructure and roughness, features that depend crucially on the growth process due to the inherent out-of equilibrium nature of the film deposition techniques. This fact suggest that it is possible to control film growth, and in turn film properties, in a knowledge-based manner by tuning the deposition conditions. This requires a good understanding of the elementary film-forming processes, and the way by which they are affected by atomic-scale kinetics. The kinetic Monte Carlo (kMC) method is a simulation tool that can model film evolution over extended time scales, of the order of microseconds, and beyond, and thus constitutes a powerful complement to experimental research aiming to obtain an universal understanding of thin film formation and morphological evolution. In this work, kMC simulations, coupled with analytical modelling, are used to investigate the early stages of formation of metal films and nanostructures supported on weakly-interacting substrates. This starts with the formation and growth of faceted 3D islands, that relies first on facile adatom ascent at single-layer island steps and subsequently on facile adatom upward diffusion from the base to the top of the island across its facets. Interlayer mass transport is limited by the rate at which adatoms cross from the sidewall facets to the island top, a process that determines the final height of the islands and leads non-trivial growth dynamics, as increasing temperatures favour 3D growth as a result of the upward transport. These findings explain the high roughness observed experimentally in metallic films grown on weakly-interacting substrates at high temperatures. The second part of the study focus on the next logical step of film formation, when 3D islands come into contact and fuse into a single one, or coalesce. The research reveals that the faceted island structure governs the macroscopic process of coalescence as well as its dynamics, and that morphological changes depend on 2D nucleation on the II facets. In addition, deposition during coalescence is found to accelerate the process and modify its dynamics, by contributing to the nucleation of new facets. This study provides useful knowledge concerning metal growth on weakly-interacting substrates, and, in particular, identifies the key atomistic processes controlling the early stages of formation of thin films, which can be used to tailor deposition conditions in order to achieve films with unique properties and applications.
25
Pauthe, Emmanuel. "Approches cinétiques et moléculaires de la reconnaissance enzyme-substrat : application à l'étude de l'activité protéolytique de la thermolysine." Compiègne, 1998. http://www.theses.fr/1998COMP1139.
Анотація:
L’accomplissement de tout acte protéolytique implique nécessairement la formation d'un complexe entre l'enzyme et son substrat. Par différentes approches cinétiques, spectroscopiques et moléculaires nous avons cherché à caractériser les phénomènes mis en jeu au cours de l'hydrolyse, par la thermolysine, de petits peptides en milieu biomimétiques. Cette étude a été conduite à l'interface entre la biochimie, la biophysique, la chimie et la physique. Dans un premier temps, nous nous sommes intéressés au comportement catalytique de la thermolysine sur des substrats modèles et en milieu modifié. Nous avons montré d'une part, que l'ajout d'additifs polyhydroxylés influence grandement l'activité de la thermolysine et d'autre part, affine les connaissances sur la spécificité et la sélectivité de cette enzyme (en particulier, mise en évidence de l'influence du résidu P'2 dans le mécanisme). Dans un deuxième temps, nous présentons des études structurales des peptides substrats en milieu modifié. Nous avons mis en évidence l'absence d'influence du micro-environnement contenant une forte proportion de glycérol sur la conformation des molécules de substrat et le rôle possible de leur structure tridimensionnelle quant à leur hydrolyse. Ces études ont été étendues à un autre modèle peptidique, de forme cyclique ou linéaire, et corrélées aux résultats cinétiques. Dans un troisième temps, par deux approches différentes, nous avons abordé l'étude des relations structure-fonction de la thermolysine. Expérimentalement, par des études cinétiques avec l'enzyme immobilisée et des déterminations de sa structure par spectroscopie laser Raman, nous montrons que l'enzyme est très peu sensible au micro-environnement. Théoriquement en analysant, par modélisation, l'interaction de la thermolysine avec un tripeptide substrat, nous avons mis en évidence des changements de conformation du substrat et/ou des mouvements du site actif enzymatique au cours de l'acte catalytique.
26
Kausar, Rehana. "Surface studies of silicon carbide deposition on carbon and tungsten substrates." Thesis, University of Salford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314000.
27
Taylor, Sean Caldwell. "The interaction of the glycoprotein folding sensor, UDP-glucose:glycoprotein glucosyltransferase, with glycoprotein substrates /." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84438.
Анотація:
The lumen of the endoplasmic reticulum (ER) provides a specialized environment to assure the folding and oligomerization of secretory proteins to their native conformations. UDP-glucose:glycoprotein glucosyltransferase (UGGT) is a biosensor in the ER that detects the folding state of glycoproteins. UGGT-catalyzed monoglucosylation of incompletely folded glycoproteins leads to their continued retention in the ER through their association with the lectins calnexin and calreticulin for further folding or for degradation. Purified recombinant UGGT from rat liver and glycoprotein substrates from a mutant strain of Saccharomyces cerevisiae were used in an in vitro system to examine the peptide components recognized by UGGT in unfolded glycoproteins and glycopeptides. Mass spectrometry was used to measure and quantitate the levels of glucose incorporation into these substrates that was directly related to their level of recognition by UGGT. To assess the capacity of UGGT for sensing non-native structures in glycoprotein substrates, Exo-1,3-beta-glucanase (beta-Glc) from S. cerevisiae was crystallized and its structure determined. A mutagenesis strategy was used to mutate solvent-exposed residues to yield the beta-Glc F280S point mutant that retained enzymatic activity while still being recognized by UGGT. These data suggest that UGGT recognizes solvent-exposed hydrophobic patches in the primary and tertiary structure of glycoproteins even in near-native conformations.
28
Mapesa, Emmanuel Urandu. "Molecular dynamics of nanometric layers of glass formers in interaction with solid substrates." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-155709.
Анотація:
Broadband Dielectric Spectroscopy (BDS) in combination with a nanostructured electrode arrangement – which circumvents the conventional need to evaporate metal electrodes onto soft matter – is used to study the molecular dynamics of several glass forming materials
confined in nanometric (> 5 nm) layers. Other complementary experimental tools employed in this work include spectroscopic vis-Ellipsometry (SE), AC-chip calorimetry (ACC), X-ray reflectrometry (XRR), Differential Scanning Calorimetry (DSC) and Atomic Force Microscopy (AFM). The latter is used to characterize the topography of the samples and to determine their thicknesses. Under the conditions of annealing samples (Tg + 50K) in high oil-free vacuum (10E-6 mbars) for at least 12 h and carrying out measurements in inert (dry nitrogen or argon) atmosphere, it is found for all studied thin layers that the
structural relaxation, and hence the dynamic glass transition – in its mean relaxation times – remains within a margin ±3 K from the respective bulk behaviour. It is revealed, inter alia, that the one-dimensional confinement of thin films introduces restrictions on other (slower) molecular relaxation processes which manifest, depending on the specific system under investigation, as (i) an interruption of the end-to-end (normal mode) fluctuation of the chains, or (ii) a slowing down of the delta-relaxation when the system is cooled towards glass-formation. Furthermore, (iii) evidence is provided to show that the dimensionality of confinement plays a significant role in determining the resulting dynamics. A molecular understanding of these findings is given, and the discussion presented with respect to the
on-going international debate about dynamics in confinement.
29
Konpan, Martin. "Manipulation of thin metal film growth on weakly-interacting substrates using gaseous surfactants." Thesis, Linköpings universitet, Nanodesign, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158484.
Анотація:
Thin films are structures with thicknesses ranging from the atomic scale to the mesoscale that are used to alter the properties of a surface and/or serve as functional layers in devices. Thin metal films deposited from the vapor phase on weakly-interacting substrates, including oxides (TiO2, ZnO, SiO2 etc.) and two-dimensional (2D) materials (graphene, MoS2, etc), are relevant for a wide array of technological applications, such as optical devices, nanoelectronic components, sensors, and catalytic devices. The weak interaction between deposit and surface in these film/substrate combinations leads to three-dimensional (3D) metal-layer morphological evolution in an uncontrolled manner; which often constitutes an important challenge toward integrating metal layers in key enabling devices. Thus there is a need for efficient growth manipulation strategies, such that metal films with controlled 3D and 2D microstructures and morphologies can be synthesized. Surfactants, i.e., minority metal, non-metal, and gaseous species which are deployed to the growing surface together with film-forming species, have been shown to enable growth manipulation in a multitude of homo- and heteroepitaxial metal/metal and semiconductor/semiconductor systems. This work explores the viability of N2 and O2 surfactants to manipulate growth in model weakly-interacting Ag/SiO2 and Au/SiO2 systems. Au and Ag are deposited by direct current (DC) magnetron sputtering on Si substrates covered with a 500 nm thick thermally grown SiO2 layer. Gaseous N2 and O2 surfactants are introduced to the sputtering atmosphere either continuously during deposition or at well-defined points during growth, such that specific film-formation stages as targeted. Using a combination of in situ/real-time diagnostic tools and ex situ characterization techniques, it is shown that O2 and N2 cause Ag and Au, respectively, to grow flatter, i.e., 2D growth morphology is promoted. Moreover, by deploying surfactants selectively during early or late film growth stages and studying their effect on film morphological evolution, it is concluded that N2 and O2 effectively suppress the rate of island coalescence promoting formation of flatter films. The overall results of this study are the first step toward establishing an atomic-scale understanding of the effect of surfactants on morphological evolution of metal films on weakly-interacting substrates. The knowledge generated herein is relevant for designing growth manipulation strategies in a wide range of technologically important film/substrate systems.
30
Li, Yali. "Biochemical and structural studies of Escherichia coli chaperone groel-substrate interaction." [Bloomington, Ind.] : Indiana University, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3386696.
Анотація:
Thesis (Ph.D.)--Indiana University, Dept. of Biochemistry, 2009.Title from PDF t.p. (viewed on Jul 22, 2010). Source: Dissertation Abstracts International, Volume: 70-12, Section: B, page: 7367. Adviser: Lingling Chen.
31
Chauhan, Hitesh. "Protein-protein interaction and substrate channelling in the pyruvate dehydrogenase complex." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620982.
32
Douzi, Badreddine. "La machinerie de sécrétion de type II Xcp de Pseudomonas aeruginosa : relations structure-fonction et interactome." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10086.
Анотація:
Les bactéries à Gram négatif sont entourées par une enveloppe cellulaire qui, contrairement aux bactéries à Gram positif, possèdent une organisation membranaire complexe composée d’une membrane interne appelée généralement membrane cytoplasmique, un espace périplasmique contenant une matrice de peptidoglycane et une membrane externe asymétrique constituée d’une monocouche de phospholipides surmontée d’une assise de lipopolysaccharide (LPS). Afin de franchir cette barrière, les bactéries à Gram négatif ont développé différentes voies de sécrétions spécifiques dédiées à l’export des protéines (effecteurs) du milieu intracellulaire vers le milieu extracellulaire. Jusqu'à présent, six systèmes de sécrétion ont été identifiés chez ces bactéries. Chez Pseudomonas aeruginosa, une bactérie pathogène opportuniste, le système de sécrétion de type II appelé aussi sécréton Xcp constitue l’un des facteurs principales de sa virulence. Le sécréton Xcp est un complexe macromoléculaire formé par 12 protéines, nommées XcpAO et XcpPC-XcpZM. Ce complexe macromoléculaire est organisé en trois sous-complexes : i) une plateforme d’assemblage ancrée dans la membrane interne formé par les protéines XcpRESFYLZM ii) un pore de sécrétion localisé dans la membrane externe formé par l’oligomérisation d’une protéine appelé la sécrétine XcpQD. Le pore de sécrétion est connecté à la plateforme de la membrane interne par une protéine appelée XcpPC iii) un pseudopilus périplasmique sous forme de fibre hélicoïdale qui est formé par la multimérisation d’une protéine appelée la pseudopiline majeure XcpTG. D’autres protéines appelées les pseudopilines mineures XcpUH-VI-WJ-XK intègrent le pseudopilus. La première partie du travail effectué au cours de cette thèse a eu pour but d’étudier et de comprendre par des approches structurales, biochimiques et biophysiques le mécanisme d’assemblage des pseudopilines en pseudopilus. La deuxième partie de ce travail a porté sur l’étude des réseaux d’interactions entre les substrats sécrétés et les composants de la machinerie Xcp. Durant cette thèse, nous avons ainsi i) identifier grâce à l’étude des interactions protéine-protéine l’existence d’un complexe quaternaire entre les pseudopilines mineures XcpUH-VI-WJ-XK localisées au sommet du pseudopilus ii) déterminer les structures de la pseudopiline majeure XcpTG par RMN et de la pseudopiline mineure XcpWJ par cristallographie aux rayons X iii) déterminer les différents éléments du sécréton qui interagissent avec les exoprotéines du sécréton. Ce réseau d’interaction nous a permis de proposer un modèle de fonctionnement du sécréton qui élucide le cheminement des exoprotéines dans le sécréton afin qu’elles soient exportées vers le milieu extracellulaireGram-negative bacteria are characterized by a complex organization of their cell envelope composed by the inner membrane (IM) called cytoplasmic membrane, the periplasmic space containing a peptidoglycan layer and the outer membrane (OM) covered by the lipopolysaccharide matrix. Gram-negative bacteria have evolved several specialized machines called secretion systems to export their effectors from the intracellular medium to the extracellular milieu or to the host cells. Up to now, at least six secretion systems have been identified. In the opportunistic pathogen Pseudomonas aeruginosa, the type II secretion system called the Xcp secreton is the major pathway for the release of virulence factors. The Xcp secreton is a macromolecular complex composed by 12 proteins called XcpAO, XcpPC-XcpZM. This machinery is organized in 3 sub-complexes: i) the assembly platform localized in the IM implicating XcpRESFYLZM proteins ii) the OM pore composed by the oligomerization of the secretin XcpQD. The connection between the assembly platform and the secretin is performed by XcpPC anchored in the IM iii) a periplasmic pseudopilus consisting of the multimerization of the so-called major pseudopilin XcpTG. The pseudopilus is a helicoidally filament spanning the periplasmic area and pushing the substrate into the secretin pore. Four other proteins, the minor pseudopilins XcpUH-VI-WJ-XK, were found in the pseudopilus. In the present work we first focused on the study of the pseudopilus components by biochemical, biophysical and structural strategies to understand their assembly. Secondly, we investigate the protein interactome between periplasmic secreton component and secreted substrates. Thus, we revealed the presence of a quaternary complex composed by XcpUH-VI-WJ-XK located at the tip of the pseudopilus. To understand at atomic scale the regulation of the pseudopilus, we determined the structure of two components of the pseudopilus XcpTG by NMR and XcpWJ by X-ray crystallography. Using systematic protein-protein interaction studies between secreton components and purified exoproteins of Pseudomonas aeruginosa, we identified 5 proteins of the secreton able to interact with exoproteins. This interaction network allowed us to propose a model for the secretion process including the sequential steps followed by exoproteins inside the secreton to leave the cell envelop
33
Paranjape, Sulabha. "Studies of the Interaction of LCAT with Lipoprotein Substrates in HDL Deficient Plasma Systems." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc500446/.
Анотація:
Enzymatic and lipid transfer reactions involved in reverse cholesterol transport were studied in HDL deficient plasma systems. Fasting plasma samples were obtained from control and cholesterol fed guinea pigs as well as from a fish eye disease patient and were used to localize the enzyme LCAT among plasma lipoproteins (VLDL, LDL, and HDL). In both guinea pig and fish eye disease patient plasma, the LCAT activity was found in association with the HDL type particles. Cholesterol feeding in guinea pigs altered the properties of lipoprotein substrates for LCAT resulting in some changes, specifically: 1) decreased fractional rate of plasma cholesterol esterification and, 2) lower transfer of free cholesterol (FC) and esterified cholesterol (CE) within the lipoprotein fractions.
34
Chin, Wing Hong. "Identification of TrkB as a p35 interacting protein and a Cdk5 substrate /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?BICH%202005%20CHIN.
35
Meikle, Sharon. "Mutational analysis of the interaction between Raf-1 and its substrate MEK." Thesis, University of Glasgow, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269496.
36
ESSIA, NGANG JEAN-JUSTIN. "Interaction s. Cerevisiae l. Casei en fermentation alcoolique de substrats de sucrerie." Amiens, 1991. http://www.theses.fr/1991AMIES006.
Анотація:
La fermentation alcoolique industrielle de sous-produits de sucrerie, se deroule en conditions non steriles, ce qui entraine le developpement de bacteries et notamment de germes lactiques. Cette etude montre les perturbations induites par l. Casei sur s. Cerevisiae. L'acide lactique, actif par sa forme non dissociee, modifie les besoins en maintenance ainsi que le stock d'acides gras de s. Cerevisiae. Toutefois, la part du metabolite dans l'inhibition est faible et la presence de la cellule bacterienne est responsable de la reponse des levures. S. Cerevisiae favorise la croissance de l. Casei par son activite invertasique mais elle est d'autant moins inhibee que la taille de l'inoculum est importante. Un recyclage controle de la biomasse permet de rester en deca d'une population critique en contaminants
37
Khormaee, Sariah. "Optimizing siRNA Efficacy through Alteration in the Target Cell-Adhesion Substrate Interaction." Thesis, Harvard University, 2014. http://etds.lib.harvard.edu/hms/admin/view/59.
Анотація:
Short interfering RNA (siRNA) is a class of nucleotide drugs with a profound potential to improve patient health through its ability to silence the expression of specific genes at the post-transcriptional level. However, the clinical application of siRNA therapeutics remains hindered by a lack of efficient delivery systems that deposit siRNA into the cytoplasm of cells, a step necessary for siRNA’s silencing effect. Much research has focused on the development of siRNA delivery agents to overcome this challenge. There are no standard pre-clinical models for testing of siRNA delivery agents, and investigators have chosen to evaluate efficacy in a variety of systems including in vitro tissue culture and animal models. These systems have vastly different cellular microenvironments which may modulate cellular behavior and affect the response of cells to siRNA, thus altering the apparent efficacy of siRNA delivery agents. The substrate on which cells adhere is one aspect of the microenvironment that has been previously shown to alter cellular behavior. In this work, we tested the hypothesis that changing the properties of cellular adhesion substrates can change the apparent efficacy of a siRNA delivery agent. Specifically, we used a commonly employed in vitro cationic lipid siRNA delivery vector and evaluated siRNA silencing efficacy in U251 cells seeded on alginate hydrogel surfaces. These surfaces were synthesized to have systematic variation in integrin ligand arginine-glycine-aspartate (RGD) density and elastic modulus. We found that an eightfold increase in RGD content of the alginate grown substrate increased siRNA knockdown efficacy from 25 ± 12% to 52 ± 10%, with constant concentrations of siRNA and delivery agent. We found no difference in siRNA mediated knockdown efficacy over the elastic modulus range tested (53-133 kPa). These results indicate that the cell-adhesion substrate interaction can modulate siRNA protein silencing efficacy, a finding important for evaluation of siRNA therapeutics in the in vitro setting.
38
Wong, Nau Nau. "Identification and characterization of novel substrates/ interacting partners for the protein tyrosine phosphatase PRL-2." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110672.
Анотація:
The reversible process of protein phosphosphorylation by kinases and phosphatases regulates essentially every aspect of cellular processes. PRLs (Phospshatase of Regenerating Liver) are dual specificity phosphatases, belonging to the protein tyrosine phosphatase family. PRL family members (PRL-1, PRL-2 and PRL-3) possess several oncogenic properties and play an important role in tumoriogenesis and metastasis. In previous studies using multiple cellular and in vivo models, we confirmed the role of PRL-2 in cell migration and in the transformation process of breast cancer. Thus, we seek to identify the cellular pathway, mechanism of actions, and the physiological function of PRL-2. One of the most common approaches to elucidating the function of a protein is by identifying its substrates and/or interacting partners. In this study, we have identified several interesting PRL-2 interacting proteins using Affinity-Purification Mass Spectrometry (AP-MS) and we characterized the interaction with one of these candidates: cyclin M3 (CNNM3). We also generated a PRL-2 KO mouse models: these PRL2-KO mouse showed significant weight loss, suggesting PRL-2 might play an essential physiological role. We believe that the identification of PRL-2 interacting partners will shed light on the physiological functions of this PTP, and may lead to the development of new targets for breast cancer therapy.L'état de phosphorylation des protéines dans la cellule est essentiellement régulé par les kinases et les phosphatases de façon réversible. Les PRLs (Phosphatases of Regenerating Liver) sont des phosphatases à double spécificité appartenant à la famille des protéines tyrosine phosphatase. La surexpression des membres de la famille PRL (PRL-1, PRL-2 et PRL-3) est observée dans une grande variété de cancers. Ceux-ci possèdent de nombreuses propriétés oncogéniques et jouent un rôle important au niveau de la génération des tumeurs ainsi que leur dissémination métastasique. PRL-2 est la moins caractérisée de la famille PRLs. Nos études effectuées à partir de différentes lignées cellulaires ainsi que modèles in vivo ont démontrées le rôle de PRL-2 dans la migration cellulaire et le développement de tumeurs du sein. Mes recherches portent sur l'identification des voies de signalisation cellulaire modulées par PRL2 ainsi que son mécanisme d'action et son rôle physiologique. L'approche la plus commune pour comprendre la fonction d'une protéine est d'identifier ses substrats ou partenaire d'interaction. Dans cette étude, nous avons identifié plusieurs protéines interagissant avec PRL-2 in vivo par spectrométrie de masse (MS) et nous avons caractérisé son interaction avec l'un des candidats de MS : CNNM3. Nous avons aussi généré un modèle de souris knock-out (KO) de PRL-2. La souris KO manifeste une perte importante de poids suggérant un rôle physiologique important de PRL-2. Nous sommes persuadés que l'identification des substrats physiologiques de PRL2 permettra de mieux comprendre cette PTP et ainsi assurer le développement de nouvelles cibles afin de fournir un meilleur traitement contre le cancer du sein.
39
Enderlein, Carsten [Verfasser]. "Graphene and its interaction with different substrates studied by angular-resolved photoemission spectroscopy / Carsten Enderlein." Berlin : Freie Universität Berlin, 2010. http://d-nb.info/1025088174/34.
40
Jamnig, Andreas. "Thin metal films on weakly-interacting substrates : Nanoscale growth dynamics, stress generation, and morphology manipulation." Thesis, Poitiers, 2020. http://www.theses.fr/2020POIT2273.
Анотація:
La morphologie de films minces métalliques polycristallins élaborés par condensation d’une phase vapeur sur des substrats à faible interaction (SFI) possède un caractère 3D intrinsèque. De plus, la nature hors équilibre de la croissance du film depuis une phase vapeur conduit souvent à la génération de contraintes mécaniques, ce qui peut compromettre davantage la fiabilité et la fonctionnalité des dispositifs optoélectroniques. Les objectifs de cette thèse sont liés à la croissance de films métalliques sur SFI et visent à : (i) contribuer à une meilleure compréhension des processus à l'échelle atomique qui contrôlent l'évolution morphologique des films ; (ii) élucider les processus dynamiques qui régissent la génération et l'évolution des contraintes en cours de croissance ; et (iii) développer des méthodologies pour manipuler et contrôler la morphologie des films à l'échelle nanométrique. L’originalité de l’approche mise en œuvre consiste à suivre la croissance des films in situ et en temps réel par couplage de plusieurs diagnostics, complété par des analyses microstructurales ex situ. Les grandeurs mesurées sont confrontées à des modèles optiques et des simulations atomistiques.L’ensemble des résultats obtenus dans cette thèse fournissent les bases pour : (i) déterminer les coefficients de diffusion sur une large gamme de systèmes films/SFI; (ii) concevoir des stratégies non invasives pour les contacts multifonctionnels dans les dispositifs optoélectroniques;(iii) apporter des éléments de compréhension à l’origine du développement de contrainte, qui permettent de prédire et contrôler le niveau de contrainte intrinsèque à la croissance de films minces polycristallinsVapor-based growth of thin metal films with controlled morphology on weakly-interacting substrates (WIS), including oxides and van der Waals materials, is essential for the fabrication of multifunctional metal contacts in a wide array of optoelectronic devices. Achieving this entails a great challenge, since weak film/substrate interactions yield a pronounced and uncontrolled 3D morphology. Moreover, the far-from-equilibrium nature of vapor-based film growth often leads to generation of mechanical stress, which may further compromise device reliability and functionality. The objectives of this thesis are related to metal film growth on WIS and seek to : (i) contribute to the understanding of atomic-scale processes that control film morphological evolution; (ii) elucidate the dynamic competition between nanoscale processes that govern film stress generation and evolution; and (iii) develop methodologies for manipulating and controlling nanoscale film morphology between 2D and 3D.Investigations focus on magnetron sputter-deposited Ag and Cu films on SiO2and amorphous carbon (a-C) substrates. Research is conducted by strategically combining of in situand real-time film growth monitoring, ex situchemical and (micro)-structural analysis, optical modelling, and deterministic growth simulations.The overall results of the thesis provide the foundation to: (i) determine diffusion rates over a wide range of WIS film/substrates systems; (ii) design non-invasive strategies for multifunctional contacts in optoelectronic devices; (iii) complete important missing pieces in the fundamental understanding of stress, which can be used to expand theoretical descriptions for predicting and tuning stress magnitude
41
Martinez-Guerrero, Lucy Jazmin. "Substrate Influence on Ligand Interaction with the Human Multidrug And Toxin Extruder (MATE)." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/593494.
Анотація:
Organic cation (OC) secretion across renal proximal tubules (RPTs) involves basolateral OCT2- mediated uptake from the blood, followed by apical MATE1/2-mediated efflux into the tubule filtrate. Whereas OCT2 supports electrogenic OC uniport, MATE is an OC/H exchanger. OCs make up ~40% of all prescribed drugs and renal secretion plays a major role in clearing them. This study looked at two aims with the intent of resolving two outstanding issues dealing with the mechanism of MATE-mediated OC transport. First: Understanding the nature of intracellular sequestration of OC in cells that express hMATE1 as an integral part of characterizing 'the potential difference of substrate selectivity between the intracellular and extracellular face of MATE1.' Second: Testing whether structurally distinct MATE substrates can display different quantitative profiles of inhibition when interacting with structurally distinct ligands to determine 'the potential influence of the substrate on the profile of ligand interaction with MATE1.' All uptake experiments were realized with CHO cells that stably expressed hMATE1, hMATE2K or hOCT2. By epifluorescence microscopy cultured CHO-hMATE1 cells accumulated the fluorescent OC, N,N,N-trimethyl-2-[methyl(7-nitrobenzo[c][l,2,5]oxadiazol-4- yl)amino]ethanaminium (NBD-MTMA) in the cytoplasm and in a smaller, punctate compartment; accumulation in hOCT2 expressing cells was restricted to the cytoplasm. A second intracellular compartment was also evident in the multicompartmental kinetics of efflux of the prototypic OC, 1-methyl-4-phenylpyridinium, [³H]MPP, from MATE1-expressing CHO cells. Punctate accumulation (20 min) of NBD-MTMA was markedly reduced by coexposure of MATE1-expressing cells with 5 μM bafilomycin (BAF), an inhibitor of the V-Type H-ATPase, and 20 min accumulations of [³H]MPP and [³H]NBD-MTMA were reduced by >30% by coexposure with 5 μM BAF. BAF had no effect on the initial rate of MATE1-mediated uptake of NBD-MTMA (10-300 sec) suggesting that the effect of BAF was a secondary effect involving inhibition of the V-type H-ATPase. The 15 min accumulation of [³H]MPP by isolated single non-perfused rabbit RPTs was also reduced >30% by coexposure to 5 μM BAF. Thus, the native expression in RPTs of MATE protein within endosomes can increase steady-state OC accumulation. However, the rate of [³H]MPP secretion by isolated single perfused rabbit RPTs was not affected by 5 μM BAF suggesting that vesicles loaded with OCs are not likely to recycle into the apical plasma membrane at sufficient rates to provide a parallel pathway for OC secretion. The uptake of three structurally distinct MATE substrates: MPP, triethylmethylammonium (TEMA) and NBD-MTMA into CHO-hMATE1 and CHO-hMATE2K cells was inhibited by three structurally similar cationic ionic liquids (ILs, salts in the liquid state: N-butylpyridinium, NBuPy; 1-methyl-3-butylimidazolium, Bmim; and N-butyl-N-methylpyrrolidinium, BmPy). The three ILs displayed a higher affinity for the pyridinium-based NBuPy (IC50 values, 2-4 μM) than for either the pyrrolidinium- (BmPy; 20-70 μM) or imidazolium-based ILs (Bmim; 15-60 μM). Inhibition of MPP, TEMA, and NBD-MTMA transport by NBuPy was competitive, with comparable Ki values against all substrates. Bmim also competitively blocked the three substrates but with Ki values that differed significantly (20 μM against MPP and 30 μM against NBD-MTMA versus 60 μM against TEMA). By trans-stimulation, all three ILs were transported by both MATE transporters. Together, these data indicate that renal secretion of ILs by the human kidney involves MATE transporters and suggest that the mechanism of transport inhibition is ligand-dependent, supporting the hypothesis that the binding of substrates to MATE transporters involves interaction with a binding surface with multiple binding sites. In order to further verify this hypothesis the uptake of four structurally distinct MATE substrates: MPP, NBD-MTMA, Cimetidine and Metformin into CHO-hMATE1 cells was characterized. Inhibition by ~400 drugs from the NIH clinical collection (NCC) was determined, and the rank order and level of inhibition seen were comparable against all substrates. IC₅₀ were measured for ~20 drugs selected from the NCC using principal component analysis (PCA); their IC₅₀ values were very similar against all four substrates, showing no systematic influence of substrate structure on inhibitory profile. The development and comparison of pharmacophores for each individual substrate revealed no substantial difference among them as proved by cluster analysis, leading to the conclusion that contrary to what was predicted based on the preliminary IL data, the substrates tested appear to have no influence on the inhibitory profile of ligands with hMATE1.
42
Ben, Arfi Rim. "Adsorption, interaction et conformation de molécules modèles d’agent de couplage sur substrats métalliques." Mulhouse, 2007. http://www.theses.fr/2007MULH0886.
Анотація:
Le contexte de l’étude concerne les systèmes composites et notamment l’utilisation d’agents de couplage mis en œuvre pour assurer la liaison entre un substrat métallique et une matrice élastomère. Dans le cadre de cette étude, nous nous sommes intéressés plus particulièrement au cas de l’adsorption du 1-hexanedecanethiol (HS-(CH2)15-CH3) sur différents substrats, représentatifs de l’application industrielle. Par ailleurs, une étude complète a également été menée sur l’adsorption du 1-hexandécylamine (H2N-(CH2)15-CH3). Ces molécules ne diffèrent que par leur fonctionnalité terminale, la longueur de la chaîne alkyle étant identique. Elles permettront ainsi de mettre en évidence l’influence de la réactivité interfaciale sur l’adsorption. Afin de faciliter la caractérisation ultérieure des dépôts, l’étude a été réalisée sur des surfaces planes modèles. Cette étude a clairement permis de mettre en évidence l’adsorption irréversible et homogène de ces moélcules sur les différents substrats et de déterminer précisément l’interaction et l’organisation de ces molécules sondes lors de leur adsorption en surface. L’ensemble des résultats présentés dans cette étude démontrent tout l’intérêt des approches multi-techniques et multi-échelles dans la caractérisation des couches ultra-minces organiquesThe understanding of mechanisms governing the growth, the structure and the conformation of coupling agents onto different metal substrates is determinant for an optimal use in any application. A variety of analytical techniques were used to characterize the different substrates : wettability, ellipsometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS)and the polarization infrared reflection absorption spectroscopy (PM-IRRAS). Observations suggest that the structure of organic films is controlled by varying the concentration of the solution and the assembly time. The packing density, the organization and the conformation of the molecular chain depend on the nature of the metal substrate and on the roughness of the surface. All results presented in this work demonstrate the interest of multi-techniques and multi-scales approach in the characterization of ultra-thin organic films
43
Malm, Christian [Verfasser]. "Catalyst Substrate Interaction of Organo Phosphate Brønsted Acid Catalysts with Imines / Christian Malm." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2020. http://d-nb.info/1223379434/34.
44
Sharma, V. K. "COMBINATORIAL DEVELOPMENT OF NANOSTRUCTURED MATERIAL LIBRARIES FOR THE STUDY OF CELL SUBSTRATE INTERACTION." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/234157.
Анотація:
An in vivo cellular microenvironment in which cells are immobilized contribute an essential role in diverse cellular behavior, consisting of cellular morphology, dynamics and eventually cellular fate. Micro and nanofabrication tools widely used to mimic the in vivo surrounding to manipulate cellular microenvironment for elucidating underlying mechanisms of cellular processes. Following this concept, nanostructured (ns) material gradients and material libraries were developed in order to gain an insight of cell behavior on engineered substrates comprising nanotopography. This thesis highlights the development of gradients of nanostructured titania thin films attributing different roughness without influencing the chemical nature in order to understand the physical cues regulating primary cellular activities including proliferation and differentiation. The surface topographies were characterized by atomic force microscopy (AFM), chemical composition by energy dispersive X-ray spectroscopy (EDS) and wettability was investigated by contact angle measurements. PC12 cells derived from a Pheochromocytoma of the rat adrenal medulla were cultured on five different morphologies in presence of nerve growth factor (NGF) and the results suggest that the increasing roughness not only diminishes cellular attachment but also reduces the probability of differentiation and formation of focal adhesions. The second phase of the work targets the development of nanostructured material libraries for studying PC12 cell adhesion and growth. Here we described a combinatorial approach to construct libraries of metals comprising 54 physicochemical combinations induced by surface chemistry and topography. In addition the surface properties including surface topography, surface chemistry, and wettability were characterized followed by investigating cellular behavior influenced by different physicochemical conditions of nanostructured material libraries.
45
Taghian, Toloo. "Interaction of an Electric Field with Vascular Cells." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439309071.
46
Kluge, Kathrin Christiane [Verfasser]. "Characterisation of the Interaction between FAT10 and its Substrate Protein p62 / Kathrin Christiane Kluge." Konstanz : Bibliothek der Universität Konstanz, 2014. http://d-nb.info/1112745238/34.
47
Cheng, Kai. "Identification of Pctaire1 as a p35-interacting protein and a novel substrate for Cdk5 /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?BICH%202003%20CHENG.
Анотація:
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 153-177). Also available in electronic version. Access restricted to campus users.
48
Parisis, Nikolaos. "Identification of PAR-2-regulated ERK substrates and (Beta)-arrestin-interacting proteins in invasive breast cancer cells." Thesis, University of Essex, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520107.
49
Williams, Gareth Allen. "Kinetic and structural consequences of modifications to the substrate interaction site of Horseradish peroxidase C." Thesis, University of Sussex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412661.
50
DE, CROUY CHANEL AXELLE. "Interaction entre les machines chaperons dnak/dnaj/grpe et groel/groes et leurs proteines substrats." Paris 7, 1997. http://www.theses.fr/1997PA077103.
Анотація:
Les molecules chaperons forment une classe de proteine qui fixent selectivement les polypeptides naissants, non replies, mal replies, ou agreges, en reconnaissant des regions hydrophobes exposees par les proteines depliees. Cette propriete est la base de l'implication des machines chaperons (dnak/dnaj/grpe) et (groel/groes) dans des processus cellulaires tels que le repliement, l'adressage, la renaturation des proteines, et le controle des interactions proteine-proteine. Les chaperons fonctionnent en collaboration avec leur cochaperon. Nous avons etudie l'interaction entre les machines chaperons d'e. Coli et leurs substrats proteiques et l'effet produit par la presence des cochaperons. Groes diminue la specificite de groel pour les acides amines hydrophobes et augmente celle pour les acides amines hydrophiles. Dnaj attenue les sites hydrophobes de dnak cependant qu'il renforce le site arg/lys. Par ailleurs, dnaj augmente significativement l'interaction entre dnak et les peptides en helice. Au contraire des hsp90 qui semblent interagir avec de nombreuses proteines natives, dnak et groel interagissent principalement avec des proteines depliees. Cependant, nous avons montre que dnak et groel interagissent plus frequemment qu'on ne le suppose avec les proteines natives. L'affinite de dnak est en correlation avec l'hydrophobicite de surface des proteines natives. Nous avons etudie l'interaction entre dnak et les proteines membranaires, et nous avons montre que dnak interagit fortement avec les proteines membranaires solubilisees et beaucoup moins avec celles inserees dans les membranes. Enfin, dans une etude in vitro, nous avons montre que dnaj presente une activite proteine disulfure isomerase. Et nous presentons en plus, un travail portant sur l'expression et l'etat d'oxydoreduction des proteines d'e. Coli dans des mutants redox et notamment des mutants de dnaj.