Probing Structural and Motional Features of the C-Terminal Part of the Human Centrin 2/P17-XPC Microcrystalline Complex by Solid-State NMR Spectroscopy

International audienceAn insight into structural and motional features of the C-terminal part of the Human Centrin 2 in complex with the peptide P17-XPC was obtained by using complementary solid-state NMR methods. We demonstrate that the experimental conditions and procedures of sample crystallization determine not only the quality of solid-state NMR spectra but can also dramatically modify the dynamic state of water molecules and the internal mobility of the protein. Two-dimensional (2D) 13C - 13C and 15N - 15N correlation spectra reveal intra- and inter-residue dipolar connectivities and provide partial, site-specific assignments of 13C and 15N resonance signals. The secondary structure of the C-ter HsCen2 /P17-XPC complex in a microcrystalline state appears similar to that found in solution. Conformational flexibility is probed through relaxation-compensated measurements of dipolar order parameters that exploit the dynamics of cross-polarization in multidimensional experiments. The extracted dipolar coupling constants and relevant order parameters reveal increased backbone flexibility of the loops except for residues involved in coordination with the Ca2+ cation that stabilizes the hydrophobic pocket containing the peptide P17-XPC

Mise au point études des charbons par rmn du carbone-13 haute résolution à l'état solide. progrès récents et perspectives

Les principes de la RMN haute résolution dans les solides : découplage dipolaire (DD), rotation à l'angle magique (RAM), polarisation croisée (PC) sont brièvement rappelés pour application au cas des charbons. Les problèmes spécifiques à ce type d'analyse sont passés en revue de manière critique: quantitativité des mesures, notamment pour la détermination du facteur d'aromaticité; mesures à haut champ; déphasage dipolaire; méthodes pour augmenter la résolution structurale. Quelques exemples typiques illustrent cette discussion

Proton T1 and T2 relaxation times of wood components using 13C CP/MAS NMR.

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Cross polarization/magic angle spinning 13C-NMR characterization of steam exploded poplar wood.

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Relative susceptibility of the Iα and Iβ phases of cellulose towards acetylation

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Chemical characterization and agronomic effectiveness of phosphorus applied as a polyphosphate-chitosan complex

This work was undertaken to characterize a chitosan-polyphosphate complex (CH-PP) and to evaluate its agronomic effectiveness as a source of phosphorus for ryegrass (Lolium perenne) grown on loamy and clayey soils. High resolution solid state31P and13C nuclear magnetic resonance were used to characterize this complex and to monitor the structural changes occurring to it during an 8-week incubation period in a loamy soil. A pot experiment was conducted on the two soils after labelling the available P with32PO4 ions. This experiment allowed for the determination of the agronomic effectiveness of the chitosan-polyphosphate complex compared to polyphosphate and to monocalcium phosphate. Results showed that chitosan immobilized up to 147 mg P kg–1 as pyrophosphate and hexametaphosphate. This reaction did not involve major structural changes in the pyrophosphate or hexametaphosphate groups nor in the chitosan. The chitosan-polyphosphate complex was as efficient as the polyphosphate alone to sustain the P nutrition of ryegrass. The relative agronomic effectiveness of these P sources was slightly lower compared to that of monocalcium phosphate. The high P fertilizing value of the chitosan-polyphosphate complex was attributed to its gradual hydrolysis in the soil. The potential interest of chitosan to remove polyphosphates from waste waters while preserving the high P fertilizing value of polyphosphates was addressed

Médiation chimique et structuration des communautés d'hyménoptères parasites du mutualisme figuier / pollinisateur

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF