Bibliographies thématiques / Protein oligomers

Littérature scientifique sur le sujet « Protein oligomers »

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Publié le 10 mars 2023

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Articles de revues sur le sujet "Protein oligomers"

1

Schmid, J. A., H. Just et H. H. Sitte. « Impact of oligomerization on the function of the human serotonin transporter ». Biochemical Society Transactions 29, no 6 (1 novembre 2001) : 732–36. http://dx.doi.org/10.1042/bst0290732.

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The formation of oligomeric structures has been proposed for a large number of membrane proteins, including G-protein-coupled receptors and ion channels. Biochemical studies employing gel filtration, cross-linking or co-immunoprecipitation techniques showed that the serotonin [5-hydroxytryptamine (5-HT)] transporter is also capable of forming oligomers. We investigated whether the human serotonin transporter (hSERT) can be visualized as an oligomer in the plasma membrane of intact cells. To test this working hypothesis, we generated fusion proteins of hSERT and spectral variants of green fluorescent protein [cyan and yellow fluorescent proteins (CFP and YFP, respectively)]. When expressed in HeLa or HEK-293 cells, the resulting fusion proteins (CFP-hSERT and YFP-hSERT) were inserted into the plasma membrane and were indistinguishable from wild-type hSERT on functional testing (5-HT uptake assays, inhibition of 5-HT uptake by blockers such as imipramine). Oligomers were visualized by fluorescence resonance energy transfer (FRET) microscopy in living cells using complementary methods. Interestingly, oligomerization was not confined to hSERT; FRET was also observed between CFP-and YFP-labelled rat γ-aminobutyric acid transporter. Gel filtration experiments showed that most of the protein was recovered as higher molecular weight complexes; almost no monomeric form was detected. This indicates that the homo-oligomeric form is the favoured state of hSERT in living cells. The formation of oligomers was not significantly affected by co-incubation with transporter substrates or blockers. Based on our observations, oligomer formation might not be essential for the physiological function of the transporter protein, the re-uptake of substrates. Furthermore, we conclude that constitutive oligomer formation might be a general property of Na+/Cl−-dependent neurotransmitter transporters.
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Eisenberg, David, Arthur Laganowsky, Cong Liu, Michael Sawaya, Julian Whitelegge, Minglei Zhao, Angela Soriaga et al. « Structural Studies of the Amyloid State of Proteins ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C797. http://dx.doi.org/10.1107/s205327331409202x.

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Amyloid diseases, including Alzheimer's, Parkinson's, and the prion conditions, are each associated with a particular protein in fibrillar form. At the morphological level, these fibers appear similar and are termed "amyloid." We found that the adhesive segments of amyloid fibers are short protein sequences which form pairs of interdigitated, in-register beta sheets. These amyloid fibrils were long suspected to be the disease agents, but evidence suggests that in the neurodegenerative diseases, smaller, often transient and polymorphic oligomers are the toxic entities. We have identified a segment of the amyloid-forming protein, alphaB crystallin, which forms an oligomeric complex exhibiting properties of other amyloid oligomers: beta-sheet-rich structure, cytotoxicity, and recognition by an anti-oligomer antibody. The X-ray-derived atomic structure of the oligomer reveals a cylindrical barrel, formed from six anti-parallel, out-of-register protein strands, which we term a cylindrin. The cylindrin structure is compatible with sequence segments from the Abeta protein of Alzheimer's disease and from other amyloid proteins. Cylindrins offer models for the hitherto elusive structures of amyloid oligomers, and are distinct in structure from amyloid fibrils.
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Tanner, John J. « Empirical power laws for the radii of gyration of protein oligomers ». Acta Crystallographica Section D Structural Biology 72, no 10 (15 septembre 2016) : 1119–29. http://dx.doi.org/10.1107/s2059798316013218.

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The radius of gyration is a fundamental structural parameter that is particularly useful for describing polymers. It has been known since Flory's seminal work in the mid-20th century that polymers show a power-law dependence, where the radius of gyration is proportional to the number of residues raised to a power. The power-law exponent has been measured experimentally for denatured proteins and derived empirically for folded monomeric proteins using crystal structures. Here, the biological assemblies in the Protein Data Bank are surveyed to derive the power-law parameters for protein oligomers having degrees of oligomerization of 2–6 and 8. The power-law exponents for oligomers span a narrow range of 0.38–0.41, which is close to the value of 0.40 obtained for monomers. This result shows that protein oligomers exhibit essentially the same power-law behavior as monomers. A simple power-law formula is provided for estimating the oligomeric state from an experimental measurement of the radius of gyration. Several proteins in the Protein Data Bank are found to deviate substantially from power-law behavior by having an atypically large radius of gyration. Some of the outliers have highly elongated structures, such as coiled coils. For coiled coils, the radius of gyration does not follow a power law and instead scales linearly with the number of residues in the oligomer. Other outliers are proteins whose oligomeric state or quaternary structure is incorrectly annotated in the Protein Data Bank. The power laws could be used to identify such errors and help prevent them in future depositions.
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Vaikath, Nishant, Indulekha Sudhakaran, Ilham Abdi, Vijay Gupta, Nour Majbour, Simona Ghanem, Houari Abdesselem, Kostas Vekrellis et Omar El-Agnaf. « Structural and Biophysical Characterization of Stable Alpha-Synuclein Oligomers ». International Journal of Molecular Sciences 23, no 23 (23 novembre 2022) : 14630. http://dx.doi.org/10.3390/ijms232314630.

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The aggregation of α-synuclein (α-syn) into neurotoxic oligomers and fibrils is an important pathogenic feature of synucleinopatheis, including Parkinson’s disease (PD). A further characteristic of PD is the oxidative stress that results in the formation of aldehydes by lipid peroxidation. It has been reported that the brains of deceased patients with PD contain high levels of protein oligomers that are cross-linked to these aldehydes. Increasing evidence also suggests that prefibrillar oligomeric species are more toxic than the mature amyloid fibrils. However, due to the heterogenous and metastable nature, characterization of the α-syn oligomeric species has been challenging. Here, we generated and characterized distinct α-syn oligomers in vitro in the presence of DA and lipid peroxidation products 4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE). HNE and ONE oligomer were stable towards the treatment with SDS, urea, and temperature. The secondary structure analysis revealed that only HNE and ONE oligomers contain β-sheet content. In the seeding assay, both DA and ONE oligomers significantly accelerated the aggregation. Furthermore, all oligomeric preparations were found to seed the aggregation of α-syn monomers in vitro and found to be cytotoxic when added to SH-SY5Y cells. Finally, both HNE and ONE α-syn oligomers can be used as a calibrator in an α-syn oligomers-specific ELISA.
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Kreiser, Ryan P., Aidan K. Wright, Natalie R. Block, Jared E. Hollows, Lam T. Nguyen, Kathleen LeForte, Benedetta Mannini, Michele Vendruscolo et Ryan Limbocker. « Therapeutic Strategies to Reduce the Toxicity of Misfolded Protein Oligomers ». International Journal of Molecular Sciences 21, no 22 (17 novembre 2020) : 8651. http://dx.doi.org/10.3390/ijms21228651.

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The aberrant aggregation of proteins is implicated in the onset and pathogenesis of a wide range of neurodegenerative disorders, including Alzheimer’s and Parkinson’s diseases. Mounting evidence indicates that misfolded protein oligomers produced as intermediates in the aggregation process are potent neurotoxic agents in these diseases. Because of the transient and heterogeneous nature of these elusive aggregates, however, it has proven challenging to develop therapeutics that can effectively target them. Here, we review approaches aimed at reducing oligomer toxicity, including (1) modulating the oligomer populations (e.g., by altering the kinetics of aggregation by inhibiting, enhancing, or redirecting the process), (2) modulating the oligomer properties (e.g., through the size–hydrophobicity–toxicity relationship), (3) modulating the oligomer interactions (e.g., by protecting cell membranes by displacing oligomers), and (4) reducing oligomer toxicity by potentiating the protein homeostasis system. We analyze examples of these complementary approaches, which may lead to the development of compounds capable of preventing or treating neurodegenerative disorders associated with protein aggregation.
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de Klerk, G. J., et D. Engelen. « Assembly of Agrostemma githago (corn-cockle) storage proteins and their precursor proteins into oligomers ». Biochemical Journal 230, no 1 (15 août 1985) : 269–72. http://dx.doi.org/10.1042/bj2300269.

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The major fraction of seed storage proteins of Agrostemma githago (corn-cockle), a non-leguminous dicot, occurs as material with S20,w values of approximately 11S and approximately 2S, and a minor fraction as oligomers with S20,w values of approximately 6.5S. The 11S proteins are of the legumin type and consist of disulphide-linked α- and β-subunits of Mr approximately 39 000 and approximately 23 000 respectively. The oligomeric assembly of the precursor polypeptides of the 11S proteins was examined. The approximately 65 000-Mr precursor polypeptides of two 11S proteins, which consist of 38 000-25 000-Mr subunits and 36 000-22 000-Mr subunits respectively, were assembled into oligomers of approximately 7S and subsequently cleaved. Thereafter the 11S oligomer was formed. The 88 000-Mr precursor of a third 11S protein, which consists of 41 000-23 000-Mr subunits, was assembled into an approximately 8S oligomer and then cleaved, yielding two disulphide-linked intermediates of Mr 59 000 and 24 000. Thereafter, the 11S oligomer was formed. Processing of the 59 000-Mr to the 41 000-Mr polypeptide occurred both in the 8S and in the 11S form.
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Stoneman, Michael R., Naomi Raicu, Gabriel Biener et Valerică Raicu. « Fluorescence-based Methods for the Study of Protein-Protein Interactions Modulated by Ligand Binding ». Current Pharmaceutical Design 26, no 44 (22 décembre 2020) : 5668–83. http://dx.doi.org/10.2174/1381612826666201116120934.

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Background: The growing evidence that G protein-coupled receptors (GPCRs) not only form oligomers but that the oligomers also may modulate the receptor function provides a promising avenue in the area of drug design. Highly selective drugs targeting distinct oligomeric sub-states offer the potential to increase efficacy while reducing side effects. In this regard, determining the various oligomeric configurations and geometric sub-states of a membrane receptor is of utmost importance. Methods: In this report, we have reviewed two techniques that have proven to be valuable in monitoring the quaternary structure of proteins in vivo: Fӧrster resonance energy transfer (FRET) spectrometry and fluorescence intensity fluctuation (FIF) spectrometry. In FRET spectrometry, distributions of pixel-level FRET efficiency are analyzed using theoretical models of various quaternary structures to determine the geometry and stoichiometry of protein oligomers. In FIF spectrometry, spatial fluctuations of fluorescent molecule intensities are analyzed to reveal quantitative information on the size and stability of protein oligomers. Results: We demonstrate the application of these techniques to a number of different fluorescence-based studies of cells expressing fluorescently labeled membrane receptors, both in the presence and absence of various ligands. The results show the effectiveness of using FRET spectrometry to determine detailed information regarding the quaternary structure receptors form, as well as FIF and FRET for determining the relative abundance of different-sized oligomers when an equilibrium forms between such structures. Conclusion: FRET and FIF spectrometry are valuable techniques for characterizing membrane receptor oligomers, which are of great benefit to structure‐based drug design.
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Larson, Megan E., Susan J. Greimel, Fatou Amar, Michael LaCroix, Gabriel Boyle, Mathew A. Sherman, Hallie Schley et al. « Selective lowering of synapsins induced by oligomeric α-synuclein exacerbates memory deficits ». Proceedings of the National Academy of Sciences 114, no 23 (22 mai 2017) : E4648—E4657. http://dx.doi.org/10.1073/pnas.1704698114.

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Mounting evidence indicates that soluble oligomeric forms of amyloid proteins linked to neurodegenerative disorders, such as amyloid-β (Aβ), tau, or α-synuclein (αSyn) might be the major deleterious species for neuronal function in these diseases. Here, we found an abnormal accumulation of oligomeric αSyn species in AD brains by custom ELISA, size-exclusion chromatography, and nondenaturing/denaturing immunoblotting techniques. Importantly, the abundance of αSyn oligomers in human brain tissue correlated with cognitive impairment and reductions in synapsin expression. By overexpressing WT human αSyn in an AD mouse model, we artificially enhanced αSyn oligomerization. These bigenic mice displayed exacerbated Aβ-induced cognitive deficits and a selective decrease in synapsins. Following isolation of various soluble αSyn assemblies from transgenic mice, we found that in vitro delivery of exogenous oligomeric αSyn but not monomeric αSyn was causing a lowering in synapsin-I/II protein abundance. For a particular αSyn oligomer, these changes were either dependent or independent on endogenous αSyn expression. Finally, at a molecular level, the expression of synapsin genes SYN1 and SYN2 was down-regulated in vivo and in vitro by αSyn oligomers, which decreased two transcription factors, cAMP response element binding and Nurr1, controlling synapsin gene promoter activity. Overall, our results demonstrate that endogenous αSyn oligomers can impair memory by selectively lowering synapsin expression.
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Wang, Yu, Karen S. L. Lam, Ming-hon Yau et Aimin Xu. « Post-translational modifications of adiponectin : mechanisms and functional implications ». Biochemical Journal 409, no 3 (15 janvier 2008) : 623–33. http://dx.doi.org/10.1042/bj20071492.

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Adiponectin is an insulin-sensitizing adipokine with anti-diabetic, anti-atherogenic, anti-inflammatory and cardioprotective properties. This adipokine is secreted from adipocytes into the circulation as three oligomeric isoforms, including trimeric, hexameric and the HMW (high-molecular-mass) oligomeric complex consisting of at least 18 protomers. Each oligomeric isoform of adiponectin exerts distinct biological properties in its various target tissues. The HMW oligomer is the major active form mediating the insulin-sensitizing effects of adiponectin, whereas the central actions of this adipokine are attributed primarily to the hexameric and trimeric oligomers. In patients with Type 2 diabetes and coronary heart disease, circulating levels of HMW adiponectin are selectively decreased due to an impaired secretion of this oligomer from adipocytes. The biosynthesis of the adiponectin oligomers is a complex process involving extensive post-translational modifications. Hydroxylation and glycosylation of several conserved lysine residues in the collagenous domain of adiponectin are necessary for the intracellular assembly and stabilization of its high-order oligomeric structures. Secretion of the adiponectin oligomers is tightly controlled by a pair of molecular chaperones in the ER (endoplasmic reticulum), including ERp44 (ER protein of 44 kDa) and Ero1-Lα (ER oxidoreductase 1-Lα). ERp44 inhibits the secretion of adiponectin oligomers through a thiol-mediated retention. In contrast, Ero1-Lα releases HMW adiponectin trapped by ERp44. The PPARγ (peroxisome-proliferator-activated receptor γ) agonists thiazolidinediones selectively enhance the secretion of HMW adiponectin through up-regulation of Ero1-Lα. In the present review, we discuss the recent advances in our understanding of the structural and biological properties of the adiponectin oligomeric isoforms and highlight the role of post-translational modifications in regulating the biosynthesis of HMW adiponectin.
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NEMOTO, Takayuki, et Nobuko SATO. « Oligomeric forms of the 90-kDa heat shock protein ». Biochemical Journal 330, no 2 (1 mars 1998) : 989–95. http://dx.doi.org/10.1042/bj3300989.

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Two isoforms of the 90-kDa heat shock protein, HSP90α and HSP90β, are present in the cytosol of mammalian cells. Analysis by polyacrylamide gel electrophoresis under nondenaturing conditions (native PAGE) revealed that HSP90α predominantly exists as a homodimer and that HSP90β is present mainly as a monomer [Minami, Kawasaki, Miyata, Suzuki and Yahara (1991) J. Biol. Chem. 266, 10099-10103]. However, only the dimeric form has been observed under other analytical conditions such as gradient centrifugation. In this study, therefore, we investigated native forms of HSP90 by use of immunochemical techniques with isoform-specific monoclonal antibodies recently developed in our laboratory. Glycerol gradient centrifugation at the physiological salt concentration as well as native PAGE analysis of rat liver cytosol revealed oligomeric forms of HSP90α sedimenting at 8-10S as predominant ones. On the other hand, the glycerol gradient centrifugation revealed multiple forms of HSP90β oligomers sedimenting at 6-12S. All of the HSP90β oligomers, however, migrated at 100-kDa monomer and 190-kDa dimer positions on native PAGE. A novel two-dimensional double native PAGE revealed that the entity was converted from the HSP90β dimer to monomers during the electrophoresis. The same PAGE further revealed that the HSP90α oligomer also dissociated into dimers during the electrophoresis. Full-length form of bacterially-expressed human HSP90α migrated as dimers, but a considerable amount did not penetrate into the gel under native PAGE conditions, indicating the existence of oligomeric forms. Electrophoretic studies of deletion mutants of HSP90 demonstrated that the C-terminal 200 amino acids were capable of forming oligomers. Taken together, we conclude that both of the HSP90 isoforms predominantly exist as oligomeric forms in the cytosol even under unstressed conditions but that they artificially dissociate into smaller forms when subjected to native PAGE.
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Thèses sur le sujet "Protein oligomers"

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Andrade, Helena. « DNA Oligomers - From Protein Binding to Probabilistic Modelling ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-218709.

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This dissertation focuses on rationalised DNA design as a tool for the discovery and development of new therapeutic entities, as well as understanding the biological function of DNA beyond the storage of genetic information. The study is comprised of two main areas of study: (i) the use of DNA as a coding unit to illustrate the relationship between code-diversity and dynamics of self-assembly; and (ii) the use of DNA as an active unit that interacts and regulates a target protein. In the study of DNA as a coding unit in code-diversity and dynamics of self-assembly, we developed the DNA-Based Diversity Modelling and Analysis (DDMA) method. Using Polymerase Chain Reaction (PCR) and Real Time Polymerase Chain Reaction (RT-PCR), we studied the diversity and evolution of synthetic oligonucleotide populations. The manipulation of critical conditions, with monitoring and interpretation of their effects, lead to understanding how PCR amplification unfolding could reshape a population. This new take on an old technology has great value for the study of: (a) code-diversity, convenient in a DNA-based selection method, so semi-quantitation can evaluate a selection development and the population\'s behaviour can indicate the quality; (b) self-assembly dynamics, for the simulation of a real evolution, emulating a society where selective pressures direct the population's adaptation; and (c) development of high-entropy DNA structures, in order to understand how similar unspecific DNA structures are formed in certain pathologies, such as in auto-immune diseases. To explore DNA as an active unit in Tumour Necrosis Factor α (TNF-α) interaction and activity modulation, we investigate DNA's influence on its spatial conformation by physical environment regulation. Active TNF-α is a trimer and the protein-protein interactions between its monomers are a promising target for drug development. It has been hypothesised that TNF-α forms a very intricate network after its activation between its subunits and receptors, but the mechanism is still not completely clear. During our research, we estimate the non-specific DNA binding to TNF-α in the low micro-molar range. Cell toxicity assays confirm this interaction, where DNA consistently enhances TNF-α's cytotoxic effect. Further binding and structural studies lead to the same conclusion that DNA binds and interferes with TNF-α structure. From this protein-DNA interaction study, a new set of tools to regulate TNF-α's biological activity can be developed and its own biology can be unveiled.
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Rushworth, Joanne Valerie Humphrey. « The cellular prion protein as a receptor for amyloid-beta oligomers ». Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581951.

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Alzheimer's disease (AD), a progressive, neurodegenerative brain disorder, is an impending socio-economic crisis due to the aging global population. Soluble oligomers of the amyloid-β (Aβ) peptide cause neurotoxicity, synaptic dysfunction and memory impairments which underlie AD, but their mechanisms of action are poorly understood. Recently, the cellular prion protein (Prpc) was identified as a high affinity receptor which mediates the neuronal binding and memory impairments of AI3 oligomers. In this study, the cellular biology of the interaction between AI3 oligomers and Prpc was investigated. We report that fibrillar Aβ oligomers recognised by the QC antibody, which have been shown to correlate with the onset and severity of AD, bind preferentially to neuronal cells expressing Prpc. The green tea polyphenol (-)-epigallocatechin gallate (EGCG) and the red wine extract resveratrol both re-modelled the fibrillar conformation of AI3 oligomers. The resulting non-fibrillar oligomers displayed significantly reduced binding to Prpc-expressing cells and were no longer cytotoxic. Fluorescence microscopy and co-localisation with sub-cellular markers revealed that the AI3 oligomers co-internalised with Prpc, accumulated in endosomes and subsequently trafficked to Iysosomes. We report that the cell surface binding, internalisation and downstream toxicity of Aβ oligomers is dependent on the transmembrane low density lipoprotein receptor- related protein-1 (LRP1). Western blotting revealed that the binding of AI3 oligomers to cell surface Prpc impaired its ability to inhibit the activity of the l3-secretase BACE1 which cleaves the amyloid precursor protein to produce AI3. Using an siRNA approach, AI3 oligomers were found to activate the signalling molecule STEP61 in a Prpc-dependent manner. AI3 oligomers also stimulated caspase-3 activation via Prpc. These data indicate that soluble, fibrillar Aβ oligomers bind to Prpc in a conformation-dependent manner and require the transmembrane LRP1 for their cytotoxicity, thus revealing potential targets for therapeutic intervention in AD.
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Ma, Xin. « Ion Mobility Mass Spectrometry of DNA/SgrAI Nuclease Oligomers ». Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/247282.

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SgrAI is a restriction endonuclease (ENase) that cuts a long recognition sequence and exhibits self-modulation of cleavage activity and sequence specificity. Previous research has shown that SgrAI forms large oligomers when bound to particular DNA sequences and under the same conditions where SgrAI exhibits accelerated DNA cleavage kinetics. However, the detailed structure and stoichiometry of SgrAI:DNA as well as the basic building block of the oligomers, has not been fully characterized. Ion mobility mass spectrometry (IM-MS) was employed to analyze SgrAI/DNA complexes and show that the basic building block of the oligomers is the DNA-bound SgrAI dimer (DBD). The oligomers are heterogeneous containing a mixture of species with variable numbers of DBD. The collision cross sections (CCS) of the oligomers were found to have a linear relationship with the number of DBD. Models of the SgrAI/DNA oligomers were constructed and a head-to-tail arrangement was most consistent with the experimental CCS.
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Limbocker, Ryan Alexander. « Mitigating protein aggregation to reduce the toxicity inherent to Parkinson's and Alzheimer's diseases ». Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/284937.

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Protein deposition in the form of amyloid fibrils is the hallmark of more than 40 human pathologies, including Alzheimer's disease (AD) and Parkinson's disease (PD). Misfolded protein oligomers formed as intermediates during the aggregation process have been strongly implicated in the onset and progression of these diseases. In this thesis, I describe our efforts to uncover molecular agents that can reduce the toxicity caused by protein aggregation via targeting the generation, the physiochemical properties or the membrane affinity of oligomeric species. We employed an integrative approach combining in vitro techniques, including chemical kinetics, atomic force microscopy, and biophysical measurements, and in vivo methods, including neuroblastoma cells and C. elegans models of AD and PD, to identify a range of small molecules and antibodies that can suppress the toxicity related to protein aggregation through a variety of mechanisms. In Chapter 3, we show that the deleterious effects of protein aggregation can be suppressed in AD and PD worms by interfering with the aggregation rates of the amyloid-β peptide (Aβ) and the α-synuclein protein (αS). In Chapter 4, we resolve the mechanism of action for a molecule that enhances the rate of Aβ42 aggregation in AD worms with the result that toxicity is reduced, and find that it potentiates the secondary nucleation microscopic step in vitro. In Chapter 5, we characterize molecules and antibodies that modify the physiochemical properties and self-association of oligomers comprised of several proteins into clusters with reduced diffusibility. In Chapter 6, we classify a family of molecules that protect the cell by displacing several types of oligomeric species from the membrane through a generic mechanism. These results demonstrate strategies by which one can target the aggregation process to alter its resulting toxicity, provide insight into modifying the properties of the most deleterious species associated with protein aggregation and suggest that the protection of the cell from the oligomer-induced cytotoxicity associated with numerous protein misfolding diseases is a promising strategy to combat protein misfolding diseases.
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Phan, Jamie. « Investigating protein folding by the de novo design of an α-helix oligomer ». Scholarly Commons, 2013. https://scholarlycommons.pacific.edu/uop_etds/859.

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Proteins are composed of a unique sequence of amino acids, whose order guides a protein to adopt its particular fold and perform a specific function. It has been shown that a protein's 3-dimensional structure is embedded within its primary sequence. The problem that remains elusive to biochemists is how a protein's primary sequence directs the folding to adopt such a specific conformation. In an attempt to gain a better understanding of protein folding, my research tests a novel model of protein packing using protein design. The model defines the knob-socket construct as the fundamental unit of packing within protein structure. The knob-socket model characterizes packing specificity in terms of amino acid preferences for sockets in different environments: sockets filled with a knob are involved in inter-helical interactions and free sockets are involved in intra-helical interactions. Equipped with this knowledge, I sought to design a unique protein, Ksα1.1, completely de novo. The sequence was selected to induce helix formation with a predefined tertiary packing interface. Circular dichroism showed that Ksα1.1 formed α-helical secondary structure as intended. The nuclear magnetic resonance studies demonstrated formation of a high order oligomer with increased protein concentration. These results and analysis prove that the knob-socket model is a predictive model for all α-helical protein packing. More importantly, the knob-socket model introduces a new protein design method that can potentially hold a solution to the folding problem.
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Xu, Xiaojun [Verfasser], et A. S. [Akademischer Betreuer] Ulrich. « Protein-protein interactions in oligomers studied by solid-state NMR in biomembranes / Xiaojun Xu. Betreuer : A. S. Ulrich ». Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1108453198/34.

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Phan, Jamie. « Investigating protein folding by the de novo design of an α-helix oligomer : a thesis ». Scholarly Commons, 2001. https://scholarlycommons.pacific.edu/uop_etds/859.

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Proteins are composed of a unique sequence of amino acids, whose order guides a protein to adopt its particular fold and perform a specific function. It has been shown that a protein's 3-dimensional structure is embedded within its primary sequence. The problem that remains elusive to biochemists is how a protein's primary sequence directs the folding to adopt such a specific conformation. In an attempt to gain a better understanding of protein folding, my research tests a novel model of protein packing using protein design. The model defines the knob-socket construct as the fundamental unit of packing within protein structure. The knob-socket model characterizes packing specificity in terms of amino acid preferences for sockets in different environments: sockets filled with a knob are involved in inter-helical interactions and free sockets are involved in intra-helical interactions. Equipped with this knowledge, I sought to design a unique protein, Ksα1.1, completely de novo. The sequence was selected to induce helix formation with a predefined tertiary packing interface. Circular dichroism showed that Ksα1.1 formed α-helical secondary structure as intended. The nuclear magnetic resonance studies demonstrated formation of a high order oligomer with increased protein concentration. These results and analysis prove that the knob-socket model is a predictive model for all α-helical protein packing. More importantly, the knob-socket model introduces a new protein design method that can potentially hold a solution to the folding problem.
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Zych, Andrew John. « Conformational characterization of abiotic secondary structure based on aromatic stacking / ». Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008484.

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De, Giorgi Marcella. « Design and synthesis of novel thienylpyridyl oligomers as alpha helix mimetics with protein-protein interaction disrupting activity and possible biological applications ». Caen, 2012. http://www.theses.fr/2012CAEN4076.

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Les interactions protéine-protéine (IPPs) représentent une classe importante de cibles thérapeutiques. En effet, la plupart des processus cellulaires sont composées ou influencés par les IPPs et leur disfonctionnement peut entraîner de nombreuses maladies. Même si les surfaces protéiques sont généralement larges, des éléments clés sont responsables de l'interaction et de la reconnaissance protéique (hot spots). La structure secondaire la plus commune dans les protéines naturelles est l’hélice alpha et les petites molécules semblent être des candidats intéressants pour perturber ces interactions protéine-protéine. Nous nous sommes particulièrement intéressés aux protéines de la famille Bcl-2 qui sont des régulateurs importants de l'apoptose. Elles sont surexprimées dans de nombreux cancers et contribuent à l'initiation tumorale, la progression et la résistance à la thérapie anticancéreuse. Le but de notre étude est de concevoir des petites molécules capables d'interagir avec les membres anti-apoptotiques et ainsi restaurer le mécanisme de l'apoptose mitochondriale. Nous avons synthétisé une chimiothèque d'oligomères de structure thiénylpyridine. Ces foldamères d’un genre nouveau imiteraient les éléments clés d'une surface protéique en mimant l'orientation spatiale des différents substituants d’une hélice alpha. La plupart de ces composés ont été engagée dans des étude. S de modélisation moléculaire associées à des résultats de radiocristallographie afin d'évaluer la capacité de mimes d’hélice alpha. Par ailleurs, l’évaluation biologique de ces composés a été réalisée et les premiers résultats montrent que nos composés sont capables de rompre les interactions protéine-protéine
Protein-protein interactions (PPIs) are attractive targets for drug discovery. Indeed, most of cellular processes are composed or influenced by PPIs and their misregulation can result in numerous disease states. Even if proteins surfaces are generally large, some key elements are responsible of the interaction and the recognition (hot spots). The most common secondary structure in natural proteins is an alpha helix. Small molecules seem to be attractive candidates for stabilizing or disrupting protein-protein interactions based on alpha helices. We are particularly interested in Bcl-2 family proteins which are central regulators of apoptosis. They are overexpressed in many cancers and contribute to tumour initiation, progression and resistance to therapy. The aim of our study is to design small molecules able to interact with anti-apoptotic members and restore the intrinsic apoptosis mechanism. These foldamers would mimic only the key elements of a protein surface and potentially lead to small molecules having almost the full activity of a protein domain. For this, we synthesized a library of thienylpyridyl oligomers. Most of these compounds underwent molecular modeling studies based on radiocrystallography in order to evaluate the ability to mimic an alpha helix and the spatial orientation of different substituents. Moreover, biological tests have been done to evaluate the ability to induce apoptosis in cancer cells
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Fluharty, Brian Richard. « Identification of novel cellular prion protein-based compounds to block the toxicity of amyloid-beta oligomers ». Thesis, Boston University, 2013. https://hdl.handle.net/2144/12955.

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Thesis (Ph.D.)--Boston University
Alzheimer's disease (AD) is characterized by progressive dementia and accumulation of a cleavage product of the amyloid precursor protein, amyloid-β (Aβ) peptide, in the brain. Several lines of evidence suggest that soluble, oligomeric intermediates of Aβ are primarily responsible for synaptic dysfunction and the cognitive deficit observed in AD. The cellular prion protein (PrP^c), a cell surface glycoprotein involved in transmissible spongiform encephalopathies, was previously identified as a high affinity receptor for Aβ oligomers. It has been suggested that binding of Aβ oligomers to PrP^c transduces the synaptotoxic events seen in AD. The two reported binding sites of Aβ oligomers are located on the unstructured N-terminal tail of PrP^c. We show here that the soluble physiological cleavage fragment of PrP^c, N1, was necessary and sufficient for binding Aβ oligomers. This binding interaction was influenced by positively charged residues in the two binding sites and is dependent on the length ofthe sequence between them. Importantly, the addition of synthetic N1 peptide suppressed Aβ oligomer toxicity in cultured murine hippocampal neurons and in a mouse model of Aβ-induced memory dysfunction. Collectively, these data suggest that N1, or small peptides derived from it, could be potent inhibitors of Aβ oligomer toxicity by targeting Aβ oligomers and represent an entirely new class of therapeutic agents for AD. To directly target PrP^c as a toxicity receptor, in silica screening and molecular dynamics were used to generate small molecule ligands. We screened these ligands using biochemical and biophysical assays to identify high affinity ligands for PrP^c that block the binding of Aβ oligomers. We found one compound, called DS26 that bound to PrP^c with sub-micromolar affinity. Further, DS26 inhibited Aβ-dependent suppression of long-term potentiation in mouse hippocampal slices. Interestingly, we show that DS26 operated by an unexpected allosteric mechanism in which ligand binding to a site in the structured C-terminal half of PrP^c induced an intramolecular interaction with the N-terminal tail, thereby preventing Aβ binding. Together, these data demonstrate that pharmacologically targeting PrP^c can suppress Aβ toxicity. Additionally, this study clarifies previous conflicting studies regarding the role of PrP^c in AD.
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Livres sur le sujet "Protein oligomers"

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Nakamura, Tomohiro, et Stuart A. Lipton. Neurodegenerative Diseases as Protein Misfolding Disorders. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190233563.003.0002.

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Neurodegenerative diseases (NDDs) often represent disorders of protein folding. Rather than large aggregates, recent evidence suggests that soluble oligomers of misfolded proteins are the most neurotoxic species. Emerging evidence points to small, soluble oligomers of misfolded proteins as the cause of synaptic dysfunction and loss, the major pathological correlate to disease progression in many NDDs including Alzheimer’s disease. The protein quality control machinery of the cell, which includes molecular chaperones as found in the endoplasmic reticulum (ER), the ubiquitin-proteasome system (UPS), and various forms of autophagy, can counterbalance the accumulation of misfolded proteins to some extent. Their ability to eliminate the neurotoxic effects of misfolded proteins, however, declines with age. A plausible explanation for the age-dependent deterioration of the quality control machinery involves compromise of these systems by excessive generation of reactive oxygen species (ROS), such as superoxide anion (O2-), and reactive nitrogen species (RNS), such as nitric oxide (NO). The resulting redox stress contributes to the accumulation of misfolded proteins. Here, we focus on aberrantly increased generation of NO-related species since this process appears to accelerate the manifestation of key neuropathological features, including protein misfolding. We review the chemical mechanisms of posttranslational modification by RNS such as protein S-nitrosylation of critical cysteine thiol groups and nitration of tyrosine residues, showing how they contribute to the pathogenesis of NDDs.
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Moloshok, Thomas David. Oligogalacturonides as signals for plant defensive genes : Structure-activity relationships of oligomers for induction of proteinase inhibitors and for enhancement of plasma membrane protein phosphorylation. 1989.

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Wetzel, Ronald, et Rakesh Mishra. Structural Biology. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199929146.003.0012.

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The 3,144–amino acid huntingtin protein (HTT) folds in water into a structure consisting of compact, organized domains interspersed with intrinsically disordered protein (IDP) elements. The IDPs function as sites of post-translational modifications and proteolysis as well as in targeting, binding, and aggregation. Although the dominant structural motif of HTT is the α‎-helix–rich HEAT repeat, the expanded polyglutamine (polyQ) toxicity responsible for Huntington’s disease is most likely played out within intrinsically disordered HTT exon 1–like fragments consisting of the 16– to 17–amino acid N-terminal HTTNT segment, the polyQ segment, and a proline-rich segment. The physical behavior of HTT exon 1 fragments is dominated by interactive, polyQ repeat length–dependent structural transitions responsible for membrane and protein–protein interactions and the formation of tetramers, higher oligomers, amyloid fibrils, and inclusions. Understanding the basis of this solution behavior may be the key to disease mechanisms and molecular therapeutic strategies.
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Safar, Jiri G. Prion Paradigm of Human Neurodegenerative Diseases Caused by Protein Misfolding. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190233563.003.0005.

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Data accumulated from different laboratories argue that a growing number of proteins causing neurodegeneration share certain characteristics with prions. Prion-like particles were produced from synthetic amyloid beta (Aβ‎) peptides of Alzheimer’s disease (AD), from recombinant α‎-synuclein linked to Parkinson’s disease (PD), and from recombinant tau associated with frontotemporal dementias (FTD). Evidence from human prions reveals that variable disease phenotypes, rates of propagation, and targeting of different brain structures are determined by distinct conformers (strains) of pathogenic prion protein. Recent progress in the development of advanced biophysical tools identified the structural characteristics of Aβ‎ in the brain cortex of phenotypically diverse AD patients and thus allowed an investigation of the prion paradigm of AD. The findings of distinctly structured strains of human brain Aβ‎, forming a unique spectrum of oligomeric particles in the cortex of rapidly progressive cases, implicates these structures in variable rates of propagation in the brain.
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Lattman, Eaton E., Thomas D. Grant et Edward H. Snell. Shape Reconstructions from Small Angle Scattering Data. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199670871.003.0004.

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This chapter discusses recovering shape or structural information from SAXS data. Key to any such process is the ability to generate a calculated intensity from a model, and to compare this curve with the experimental one. Models for the particle scattering density can be approximated as pure homogenenous geometric shapes. More complex particle surfaces can be represented by spherical harmonics or by a set of close-packed beads. Sometimes structural information is known for components of a particle. Rigid body modeling attempts to rotate and translate structures relative to one another, such that the resulting scattering profile calculated from the model agrees with the experimental SAXS data. More advanced hybrid modelling procedures aim to incorporate as much structural information as is available, including modelling protein dynamics. Solutions may not always contain a homogeneous set of particles. A common case is the presence of two or more conformations of a single particle or a mixture of oligomeric species. The method of singular value decomposition can extract scattering for conformationally distinct species.
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Chapitres de livres sur le sujet "Protein oligomers"

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Ferré, Sergi. « Allosterism Within GPCR Oligomers : Back to Symmetry ». Dans G-Protein-Coupled Receptor Dimers, 433–50. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-60174-8_17.

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Sleno, Rory, Dominic Devost et Terence E. Hébert. « Understanding the Physiological Significance of GPCR Dimers and Oligomers ». Dans G-Protein-Coupled Receptor Dimers, 451–65. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-60174-8_18.

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Wang, Chunyu. « Solution NMR Studies of Aβ Monomers and Oligomers ». Dans Protein and Peptide Folding, Misfolding, and Non-Folding, 389–411. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118183373.ch13.

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Kandiyal, Pancham S., Ji Yoon Kim, Daniel L. Fortunati et K. H. Mok. « Size Determination of Protein Oligomers/Aggregates Using Diffusion NMR Spectroscopy ». Dans Methods in Molecular Biology, 173–83. New York, NY : Springer New York, 2019. http://dx.doi.org/10.1007/978-1-4939-9678-0_13.

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Hong, Dong-Pyo, Wenbo Zhou, Aaron Santner et Vladimir N. Uversky. « Oligomers of α-Synuclein in the Pathogenesis of Parkinson’s Disease ». Dans Non-fibrillar Amyloidogenic Protein Assemblies - Common Cytotoxins Underlying Degenerative Diseases, 189–216. Dordrecht : Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2774-8_6.

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Palacio-Castañeda, Valentina, Roland Brock et Wouter P. R. Verdurmen. « Generation of Protein-Phosphorodiamidate Morpholino Oligomer Conjugates for Efficient Cellular Delivery via Anthrax Protective Antigen ». Dans Methods in Molecular Biology, 129–41. New York, NY : Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2010-6_8.

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AbstractPhosphorodiamidate morpholino oligomers (PMOs) offer great promise as therapeutic agents for translation blocking or splice modulation due to their high stability and affinity for target sequences. However, in spite of their neutral charge as compared to natural oligonucleotides or phosphorothioate analogs, they still show little permeability for cellular membranes, highlighting the need for effective cytosolic delivery strategies. In addition, the implementation of strategies for efficient cellular targeting is highly desirable to minimize side effects and maximize the drug dose at its site of action. Anthrax toxin is a three-protein toxin of which the pore-forming protein anthrax protective antigen (PA) can be redirected to a receptor of choice and lethal factor (LF), one of the two substrate proteins, can be coupled to various cargoes for efficient cytosolic cargo delivery. In this protocol, we describe the steps to produce the proteins and protein conjugates required for cytosolic delivery of PMOs through the cation-selective pore generated by anthrax protective antigen. The method relies on the introduction of a unique cysteine at the C-terminal end of a truncated LF (aa 1–254), high-yield expression of the (truncated) toxin proteins in E. coli, functionalization of a PMO with a maleimide group and coupling of the maleimide-functionalized PMO to the unique cysteine on LF by maleimide-thiol conjugation chemistry. Through co-administration of PA with LF-PMO conjugates, an efficient cytosolic delivery of PMOs can be obtained.
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Rosensweig, Clark, Kenjiro Ono, Kazuma Murakami, Devin K. Lowenstein, Gal Bitan et David B. Teplow. « Preparation of Stable Amyloid β-Protein Oligomers of Defined Assembly Order ». Dans Methods in Molecular Biology, 23–31. Totowa, NJ : Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-551-0_3.

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Sakmar, Thomas P., Xavier Periole et Thomas Huber. « Probing Self-Assembly of G Protein-Coupled Receptor Oligomers in Membranes Using Molecular Dynamics Modeling and Experimental Approaches ». Dans G-Protein-Coupled Receptor Dimers, 385–414. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-60174-8_15.

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Morales, Rodrigo, Claudia A. Duran-Aniotz et Claudio Soto. « Role of Prion Protein Oligomers in the Pathogenesis of Transmissible Spongiform Encephalopathies ». Dans Non-fibrillar Amyloidogenic Protein Assemblies - Common Cytotoxins Underlying Degenerative Diseases, 319–35. Dordrecht : Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2774-8_10.

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Bhaskar, Kiran, et Bruce T. Lamb. « The Role of Aβ and Tau Oligomers in the Pathogenesis of Alzheimer’s Disease ». Dans Non-fibrillar Amyloidogenic Protein Assemblies - Common Cytotoxins Underlying Degenerative Diseases, 135–88. Dordrecht : Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2774-8_5.

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Actes de conférences sur le sujet "Protein oligomers"

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Intze, A., M. E. Temperini, R. Polito, E. Zacco, G. G. Tartaglia, A. Pastore, M. Ortolani et V. Giliberti. « Mid-infrared nanospectroscopy of individual DNA-binding protein oligomers ». Dans 2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz). IEEE, 2022. http://dx.doi.org/10.1109/irmmw-thz50927.2022.9895918.

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Abakumets, V. Y., et K. Ya Bulanava. « THE INFLUENCE OF INSULIN FIBRILLATION ». Dans SAKHAROV READINGS 2021 : ENVIRONMENTAL PROBLEMS OF THE XXI CENTURY. International Sakharov Environmental Institute of Belarusian State University, 2021. http://dx.doi.org/10.46646/sakh-2021-2-7-10.

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Violation of protein folding leads to the development of a number of systemic and neurodegenerative diseases-proteinopathy. In these pathologies, proteins acquire an incorrect conformation that differs from the native one, become functionally inactive, toxic, and prone to aggregation and deposition in various organs and tissues. There is a widespread hypothesis that the primary cytotoxic agents in the development of proteinopathies are protein oligomers that are prone to aggregation. These diseases include Parkinson’s disease, Creutzfeldt-Jakob disease, type 2 diabetes, and many others.
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Temirov, Jamshid, James H. Werner, Peter M. Goodwin et Andrew R. M. Bradbury. « "Sizing" the oligomers of Azami Green fluorescent protein with FCS and antibunching ». Dans SPIE BiOS, sous la direction de Jörg Enderlein, Zygmunt K. Gryczynski, Rainer Erdmann, Felix Koberling et Ingo Gregor. SPIE, 2012. http://dx.doi.org/10.1117/12.906843.

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Ide, J. P., D. R. Klug, W. Kuhlbrandt et G. Porter. « Detergent effects upon the picosecond dynamics of higher plant light harvesting chlorophyll complex (LHC). » Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 1986. http://dx.doi.org/10.1364/up.1986.mf1.

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The light-harvesting chlorophyll a/b protein complex (LHC) has been shown to form crystalline arrays in vitro. These arrays have P321 symmetry. The unit cell is composed of trimeric protein oligomers arranged with a 3-fold symmetry axis running centrally through each complex[1]. Each polypeptide has an apparent molecular weight of 25–27kd within which are bound 6-11 chlorophyll molecules.
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Stoneman, M. R., D. R. Singh et V. Raicu. « In vivo stoichiometry monitoring of G protein coupled receptor oligomers using spectrally resolved two-photon microscopy ». Dans BiOS, sous la direction de Ammasi Periasamy, Peter T. C. So et Karsten König. SPIE, 2010. http://dx.doi.org/10.1117/12.843916.

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Wu, Jeffrey, Prakash Ambady, DreeAnna Morris, Michael Pagel, Randy Woltjer, Joshua Walker, Leslie Muldoon et Edward Neuwelt. « Abstract B38 : Radiation enhances intracellular delivery of anti-MGMT oligomers to reduce protein expression in vitro and in a xenograft model ». Dans Abstracts : AACR Special Conference on DNA Repair : Tumor Development and Therapeutic Response ; November 2-5, 2016 ; Montreal, QC, Canada. American Association for Cancer Research, 2017. http://dx.doi.org/10.1158/1557-3125.dnarepair16-b38.

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Sabino, Luis G., Wellinson Gadelha Guimarães, Pedro Mikael Costa, Marta S. P. Carepo, Ana C. S. Gondim, Luiz G. F. Lopes et Eduardo H. S. Sousa. « The application of low angle light scattering to evaluate qualitatively and quantitatively the dynamics of formation of oligomers in heme protein sensors ». Dans SPIE BiOS, sous la direction de Adam Wax et Vadim Backman. SPIE, 2016. http://dx.doi.org/10.1117/12.2213733.

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Savikhin, S., et W. S. Struve. « Optical coherences in light-harvesting chlorosomes from green photosynthetic bacteria ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.tue.21.

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Chlorosomes are light-harvesting assemblies that are found in green photosynthetic bacteria [1]. The principal antenna in a chlorosome consists of ~104 bacteriochlorophyll (BChl) c, d, or e pigments, which give rise to a broad Qy electronic absorption band centered at ~ 740 nm. Excitations in the BChl c/d/e antenna are transferred to a lower- energy BChl a antenna absorbing at ~795 nm, prior to trapping at the reaction centers [2]. BChl c/d/e antennae in chlorosomes appear to be pigment oligomers whose structure is determined by pigment-pigment rather than pigment-protein interactions, because spectroscopically similar BChl aggregates self-assemble spontaneously from the pigment monomers in solution [3]. The internal energy transfer kinetics of reconstituted BChl c aggregates from the green bacteria Chloroflexus aurantiacus and Chlorobium tepidum closely resemble those found in the BChl c antennae of the intact chlorosomes [4].
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Savikhir, S., Y. Zhu, S. Lin, R. E. Blankenship et W. S. Struve. « Femtosecond energy transfer and coherent oscillations in BChl c light-harvesting antennae of chlorosomes from the green photosynthetic bacterium Chloroflexus aurantiacus ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.tub.3.

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Chlorosomes are the principal light-harvesting bodies in green photosynthetic bacteria. These 100×30×12 nm ellipsoidal bodies contain ~104 bacteriochlorophyll (BChl) c chromophores, as well as a BChl a pigment-protein complex that forms an interfacial baseplate between the chlorosome and the cytoplasmic membrane. The BChl c pigments in chlorosomes are organized into large oligomers, whose electronic and vibrational spectroscopy is remarkably similar to that of BChl c aggregates that form spontaneously from BChl c monomers in solution. This unique self-aggregating property has attracted wide attention because of its potential applications in artificial photosynthesis. The BChl c and BChl a antennae of chlorosomes from the green bacterium Chloroflexus aurantiacus exhibit broad Qy (S1←S0) electronic absorption bands centered at ~740 and ~790 nm, respectively. Downhill BChl c → BChl a energy transfer occurs with ~10 ps kinetics in isolated chlorosomes [1,2]. In this work, we have focussed on the femtosecond internal energy transfer events within the BChl c antenna. It is currently believed [3] that this 740 nm antenna comprises several distinct BChl c spectral forms (c727, c744, c766 etc.) Equilibration among chlorophyll and bacteriochlorophyll spectral forms requires several hundred fs in most pigment-protein antenna complexes that have been studied to date [4].
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Rak, K., J. Harsfalvi, M. Udavardy, I. Tornai, M. Misz et Z. Boda. « ALTERATION OF PRIMARY HAEMOSTASIS IN PATIENTS WITH ATHEROSCLEROSIS : ITS POSSIBLE ROLE IN ATHEROGENESIS ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643082.

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Complex study was performed in order to evaluate the primary haemostasis of patients with generalized atherosclerosis. Signs referring to hypercoagulability and platelet activation are known from previous studies. The purpose of this work was to investigate the primary haemostasis in every detail. Assays were performed in 20 atherosclerotic patients and 10 control persons. Methods: platelet count, Ivy bleeding time (Simplate II), platelet retention (Adeplat T), in vivo platelet consumption (Borchgrevink), study of vWFAg by Laurell’s rocket and crossed immunoelectrophoresis (using Clottimmun-AHG Assoc. Protein, Behring), plasma B-TG (Amersham), the stable metabolites of TXA2 (TXB2) and PGI2 (6-KPGF) by RIA-kits. Results: platelet counts and bleeding times were not different, in vivo platelet consumption was also similar, but platelet retention proved to be increased in patients (40 vs 27 %). Increase of vWFAg level characterized atherosclerotic patients (277±83 vs 102±28 %); the relative mobility (RM) ratio which indicates the migration distance of vWFAG in CIE was significanty altered (0.33 compared to 0.26) meaning that the molecular forms of protein with faster mobility were increased to a greater degree than forms with slow mobility. B-TG plasmatic level was increased in patients (115 vs 28 ng/ml), the quotient of TXB2 and 6-KPGF was much bigger (4.7 vs 0.4). In conclusion: the most striking change was the elevation of plasmatic vWFAg level together with its structural alteration, i.e. predominance of the smaller oligomers. Primary haemostasis seems to be more active than normal, atherosclerosis represents a hyperadhesive and/or prethrombotic state. Although all the findings may be the result of vessel wall lesions, the observed changes may also have a causal role in the progression and complications of atherosclerosis.
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Rapports d'organisations sur le sujet "Protein oligomers"

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Garcia, A. E., et G. Hummer. Theoretical studies of the interaction of water with DNA oligomers and proteins. Office of Scientific and Technical Information (OSTI), avril 1996. http://dx.doi.org/10.2172/212500.

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Sierks, Michael. Oligomeric Neuronal Protein Aggregates as Biomarkers for Traumatic Brain Injury (TBI) and Alzheimer Disease (AD). Fort Belvoir, VA : Defense Technical Information Center, octobre 2013. http://dx.doi.org/10.21236/ada591179.

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Fleming, Karen G. Energetics and Structure Prediction of the Network of Homo- and Hetero-Oligomers Formed by the Transmembrane Domains of the ErbReceptor Family of Proteins. Fort Belvoir, VA : Defense Technical Information Center, juin 2006. http://dx.doi.org/10.21236/ada456142.

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Azem, Abdussalam, George Lorimer et Adina Breiman. Molecular and in vivo Functions of the Chloroplast Chaperonins. United States Department of Agriculture, juin 2011. http://dx.doi.org/10.32747/2011.7697111.bard.

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We present here the final report for our research project entitled "The molecular and in vivo functions of the chloroplast chaperonins”. Over the past few decades, intensive investigation of the bacterial GroELS system has led to a basic understanding of how chaperonins refold denatured proteins. However, the parallel is limited in its relevance to plant chaperonins, since the plant system differs from GroEL in genetic complexity, physiological roles of the chaperonins and precise molecular structure. Due to the importance of plant chaperonins for chloroplast biogenesis and Rubisco assembly, research on this topic will have implications for many vital applicative fields such as crop hardiness and efficiency of plant growth as well as the production of alternative energy sources. In this study, we set out to investigate the structure and function of chloroplast chaperonins from A. thaliana. Most plants harbor multiple genes for chaperonin proteins, making analysis of plant chaperonin systems more complicated than the GroEL-GroES system. We decided to focus on the chaperonins from A. thaliana since the genome of this plant has been well defined and many materials are available which can help facilitate studies using this system. Our proposal put forward a number of goals including cloning, purification, and characterization of the chloroplast cpn60 subunits, antibody preparation, gene expression patterns, in vivo analysis of oligomer composition, preparation and characterization of plant deletion mutants, identification of substrate proteins and biophysical studies. In this report, we describe the progress we have made in understanding the structure and function of chloroplast chaperonins in each of these categories.
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Valente, Pedro, Luis Rama, Hugo Sarmento et Ana Teixeira. Cartilage Oligomeric Matrix Protein (COMP), a potential cartilage destruction biomarker in active and healthy individuals or athletes from different sports. A systematic review. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, février 2021. http://dx.doi.org/10.37766/inplasy2021.2.0032.

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