Littérature scientifique sur le sujet « Cristallographie RMN »
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Articles de revues sur le sujet "Cristallographie RMN":
Cadars, Sylvian, Mathieu Allix, Franck Fayon, Emmanuel Véron et Dominique Massiot. « Complémentarité de la RMN, la modélisation et la diffraction pour une cristallographie des systèmes désordonnés ». Reflets de la physique, no 44-45 (juillet 2015) : 50–55. http://dx.doi.org/10.1051/refdp/20154445050.
Thèses sur le sujet "Cristallographie RMN":
Bouchevreau, Boris. « Détermination structurale de matériaux inorganiques par cristallographie RMN ». Versailles-St Quentin en Yvelines, 2013. http://www.theses.fr/2013VERS0073.
Structure determination of hybrid solids by powder diffraction only is still a great challenge preventing a better understanding of their properties. For nanoporous materials with more and more complex architectures, an additional difficulty arises from the combinatorial explosion of computation time with the increased number of atoms. Therefore, the present Thesis had for objective the development of a strategy based on nuclear magnetic resonance (NMR) data to drive the structure determination from powder diffraction. The tools necessary to apply this strategy (tools for space group selection, for NMR line assignment, for the analysis of the structure topology, new NMR experiments for better resolution…) have been adapted or developed in the context of the structural study of aluminophosphates. The efficiency of the method, in particular the strong decrease in computation time it provides, has been illustrated with the examples of two layered aluminophosphates. Diffraction techniques usually ignore the non-periodic parts of crystals. Solid-state NMR, more sensitive to local order, provides structural information complementary to those extracted from diffraction data. With this in mind, the structure of several aluminophosphates, fluorinated or not, has been re-investigated by NMR Crystallography. The very high-resolution obtained using state-of-the-art NMR experiments has allowed the accurate location of the fluoride ions, hydroxyl groups, water molecules (including dehydration/rehydration processes) and template molecules in these solids. From this ensemble of data, simple rules describing distribution of these species and their potential templating roles have emerged
Dekhil, Myriam. « RMN cristallographique : mesure de distances internucléaires sur des échantillons de poudre par RMN du solide ». Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4734.
Measurment of dipolar coupling provides 3D structural information of powder samples. However, in practice, the high density of spins in organic compounds prevents the measurements of long-range dipolar couplings in solid-state NMR by the so-called dipolar truncation effect. The study of rare spins on natural abundance allows to overcome this problem. In fact, with a natural abundance of 1.1 %, the probability for three 13C to be coupled is negligible. We developed a methodology based either on the dipolar recoupling NMR pulse sequence POST-C7 or on the dramatic increase in sensitivity provided by dynamic nuclear polarization. We demonstrated that its methodology provides a measure of 13C-13C dipolar couplings in natural abundance powder samples and that the so-obtained distance information is sensitive to both molecular conformation and crystal packing of powder samples. Moreover, we show that the recoupling pulse sequence R20_9_2 is more robust to strong chemical shift anisotropy and also to strong 1H-13C heteronuclear dipolar couplings than POST-C7. The second challenge involves 13C signal assignment for natural abundance. In fact, there are only a few examples of 13C-13C correlation spectra obtained for natural abundance samples. Here, we show that 13C-13C correlation spectra sequence based on the reintroduction of 13C−13C dipolar couplings can be obtained with standard MAS probe and within few days using R20_9_2 pulse sequence. Contrary to pulse sequences based on 13C-13C J coupling, our pulse sequence requires shorter DQ excitation time and hence, is more suitable for samples having short T2 relaxation times such as amorphous solids
Dekhil, Myriam. « RMN cristallographique : mesure de distances internucléaires sur des échantillons de poudre par RMN du solide ». Electronic Thesis or Diss., Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4734.
Measurment of dipolar coupling provides 3D structural information of powder samples. However, in practice, the high density of spins in organic compounds prevents the measurements of long-range dipolar couplings in solid-state NMR by the so-called dipolar truncation effect. The study of rare spins on natural abundance allows to overcome this problem. In fact, with a natural abundance of 1.1 %, the probability for three 13C to be coupled is negligible. We developed a methodology based either on the dipolar recoupling NMR pulse sequence POST-C7 or on the dramatic increase in sensitivity provided by dynamic nuclear polarization. We demonstrated that its methodology provides a measure of 13C-13C dipolar couplings in natural abundance powder samples and that the so-obtained distance information is sensitive to both molecular conformation and crystal packing of powder samples. Moreover, we show that the recoupling pulse sequence R20_9_2 is more robust to strong chemical shift anisotropy and also to strong 1H-13C heteronuclear dipolar couplings than POST-C7. The second challenge involves 13C signal assignment for natural abundance. In fact, there are only a few examples of 13C-13C correlation spectra obtained for natural abundance samples. Here, we show that 13C-13C correlation spectra sequence based on the reintroduction of 13C−13C dipolar couplings can be obtained with standard MAS probe and within few days using R20_9_2 pulse sequence. Contrary to pulse sequences based on 13C-13C J coupling, our pulse sequence requires shorter DQ excitation time and hence, is more suitable for samples having short T2 relaxation times such as amorphous solids
Salager, Elodie. « High-resolution solid-state NMR for powder crystallography ». Lyon, Ecole normale supérieure, 2010. http://www.theses.fr/2010ENSL0592.
Knowledge of the three-dimensional structure is an invaluable element for the understanding of the properties of solid materials and towards the development of new materials. While single-crystal X-ray diffraction is established as the best tool to characterise monocrystalline samples, the experimental determination of the structure of polycrystalline powders remains a challenging domain. Many crystalline solids cannot be prepared as single crystals and must be characterized in the powder form. Other compounds are highly subject to polymorphism, and there is a need for structural determination techniques that minimize the risk of structural change during the characterisation. The problem is particularly relevant in the case of drug powders, which need to be accurately characterized in their active pharmaceutical form. This thesis presents new developments relating to powder nuclear magnetic resonance (NMR) crystallography, i. E. Structure determination of powdered samples using high-resolution solid-state NMR at natural isotopic abundance. The first part of the thesis concentrates on the challenging case of protons and illustrates the opportunities offered by the latest generation of commercial NMR probes and new decoupling methods. Protocols are proposed in the second part, which benefit of the high-resolution solid-state NMR spectra accessible for protons and carbons and which make use of the strong dependence of the NMR parameters on crystalline structure details. These techniques are successfully applied to a model compound, thymol, and demonstrate the potential of solid-state NMR for structural determination of powdered compounds
Mifsud, Nicolas. « Détermination Structurale de Solides Ordonnés et Désordonnés par Spectroscopie RMN Haute Résolution ». Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2007. http://tel.archives-ouvertes.fr/tel-00175539.
Maurice, Frédérique. « Plasticité structurale et émergence d'antibiorésistance à large spectre : étude d'une aminoglycoside acétyltransférase et recherche d'inhibiteurs ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00336237.
Baudin, Antoine. « Études structurales de ligands peptidomimétiques de TRAIL complexés au récepteur de mort DR5 ». Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0424/document.
Apoptosis plays a protective role against the formation of tumor cells. This phenomenon can be regulated by the death receptor pathway, among which the Death Receptor 5 that can be activated by the TRAIL ligand (Tumor necrosis factor-Related Apoptosis Induction Ligand), whose major interest is to induce tumor cell apoptosis, specifically. Our work focuses on peptidomimetic ligands of TRAIL: those 16 amino acid peptides exist as monomers or multimers and show affinity for DR5 protein as up to 5-fold the affinity of TRAIL. Functional assays have shown that not only those ligands induce in vitro apoptosis of tumor cells, but also show selectivity for cancer cells, and can reduce mice tumor volume in vivo. The purpose of this project is to characterize the mechanisms by which those ligands interact with DR5, by using Nuclear Magnetic Resonance (NMR) and X-Ray Crystallography. We have produced the recombinant extracellular domain of DR5 in fusion with the NusA protein, in order to increase the folding of the protein, and we have purified the receptor through a 4-step protocol. We assigned the backbone resonances of 89 % of the protein residues with NMR, and secondary structure calculations showed that DR5 adopts the same β strand folding in solution as from the DR5 crystal structures from the PDB (Protein Data Bank). NMR titrations of DR5 with monomeric and multimeric ligands have allowed us to identify the peptide-protein binding area within the first Cystein Rich Domain (CRD1) of the receptor, but also that the binding with oligomeric peptides lead to protein-protein interactions at the level of the CRD2, suggesting the dimerization of the receptor. This was confirmed par Size Exclusion Chromatography assays that showed an oligomerization of the receptor in the presence of dimeric and trimeric peptides. Ongoing crystallography assays are conducted in order to determine the 3D structure at the atomic level of oligomeric complexes with DR5. Our results show that peptidomimetic ligands of TRAIL display a different mechanism from TRAIL in the activation of apoptosis
Martinez, Denis. « Rôles des phosphoinositides dans l'intéraction membranaire de la protéine Rgd1 et la croissance polarisée des levures : étude structurale et interaction par RMN et cristallographie ». Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0369/document.
Phosphoinositides act as regulatory and signalling molecules at the membrane-cytosol interface in signal transduction, membrane traffic and cytoskeleton organization. These lipids recruit several proteins to specific compartments, but also regulate their activity. In the yeast Saccharomycescerevisiae, they directly bind the Rgd1-RhoGAP domain, that stimulates the GTPase activity of bothRho3p and Rho4p. The GTPase activity of these two Rho proteins, respectively involved in the polarized growth and cytokinesis of the yeast, is enhanced with the presence of Rgd1p and PIPs. The main objective of this thesis is to understand the PIP-RhoGAP interaction at the molecular level. In order to do that, we coupled X-ray structure determination to solution NMR spectroscopy on the isolated RhoGAP domain. Our results show that the domain contains the conserved elements that would usually confer the catalytic GTPase activation. We us e liquid-state NMR spectroscopy to follow the interaction with PI(4)P and PI(4,5)P2, respectively found in secretion vesicles and the plasma membrane. Our study reveals a common binding site for both PIPs in a non-conserved region in the RhoGAP domain family. We measured sub-millimolar binding affinity for PIPs. Such moderate binding affinities are consistent with the biological requirement for reversible complex formation. The selectivity of the interaction could be made in a spatio temporal way, on the secretion vesicles during polarized growth and at the plasma membrane during cytokinesis
Mifsud, Nicolas. « Structure determination in ordered and disordered solids by high-resolution NMR spectroscopy ». Lyon, École normale supérieure (sciences), 2007. http://www.theses.fr/2007ENSL0418.
La résonance magnétique nucléaire du solide est un outil potentiellement puissant pour déterminer la structure et la dynamique d’une large variété de composés. Dans cette thèse, nous montrons tout d’abord comment assigner un échantillon en poudre et en abondance isotopique naturelle à une structure cristalline en utilisant la RMN du solide haute résolution proton et carbone associée à des calculs théoriques. De même, la détermination de la structure tridimensionnelle d’un composé organique en poudre et en abondance isotopique naturelle est présentée. Elle est obtenue par une méthode qui combine modélisation moléculaire et données expérimentales de diffusion de spin proton. Enfin, une étude de la dynamique et du désordre structural a été réalisée sur des matériaux composés de silice par l’intermédiaire de la RMN du silicium. Ainsi, on montre que le temps de déphasage transverse T2’ du silicium peut être utilisé comme une sonde de la dynamique indépendamment du désordre statique
Richet-Tuillière, Nicolas. « Etude biochimique et structurale de deux complexes macromoléculaires à AAA+ ATPases : le protéasome 26S et le réplisome. Mode d’assemblage de la sous-unité Rpt1 du protéasome 26S et rôle secondaire de la sous-unité Mcm2 du réplisome dans le transfert intergénérationnel des histones ». Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066099/document.
AAA+ ATPases are involved in numerous molecular complexes. These proteins form homomeric or heteromeric hexamers and constitute molecular motors. During my Ph. D., I focused my work on two macromolecular complexes composed of AAA+ ATPases: the 26S proteasome regulatory particle and the Mcm2-7 helicase of the replisome. These complexes are implicated in the development of cancers and constitute interesting therapeutic targets. The 26S proteasome is the main machinery responsible for the regulated degradation of poly-ubiquitinated proteins and the helicase Mcm2-7 is responsible for the unwinding of the DNA during replication. These two complexes are composed of a heterohexameric ring of six AAA+ ATPases called Rpt1 to 6 for the 26S proteasome regulatory particle and Mcm2 to 7 for the replisome. I have studied the role of Hsm3/S5b in the assembly mechanism of the proteasome and the specific role of the subunit Mcm2 in the intergenerational transfer of the epigenetic information. X-ray structures of the complexes Hsm3-Rpt1 and S5b-Rpt1 allowed us to elucidate the dual functions of the assembly chaperone Hsm3/S5b which mediates the assembly of the subcomplex Rpt1-Rpt2-Rpn1 during the assembly of the regulatory particle. In addition, hsm3/S5b inhibits the association of a premature regulatory particle onto the core particle and protects the HbYX motif of Rpt1. Other AAA+ ATPases, like the replisome subunits, possess additional domains which confer specific roles. I also studied the interaction between the N-terminal domain of Mcm2 and the tetrameric form of histones H3-H4 by several methods like X-ray crystallography, NMR and SEC-MALS. I propose a model of the intergenerational transfer of histones H3-H4 in which Mcm2 plays a crucial role of molecular histones chaperone directly integrated in the replication machinery