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Water scaffolding in collagen: Implications on protein dynamics as revealed by solid‐state NMR
Author(s) -
Aliev Abil E.,
CourtierMurias Denis
Publication year - 2014
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.22330
Subject(s) - chemistry , microsecond , hydrogen bond , bound water , dephasing , solid state nuclear magnetic resonance , crystallography , molecular dynamics , protein dynamics , proton nmr , water content , chemical physics , analytical chemistry (journal) , computational chemistry , nuclear magnetic resonance , stereochemistry , organic chemistry , molecule , physics , geotechnical engineering , quantum mechanics , astronomy , engineering
Solid‐state NMR studies of collagen samples of various origins confirm that the amplitude of collagen backbone and sidechain motions increases significantly on increasing the water content. This conclusion is supported by the changes observed in three different NMR observables: (i) the linewidth dependence on the 1 H decoupling frequency; (ii) 13 C CSA changes for the peptide carbonyl groups, and (iii) dephasing rates of 1 H‐ 13 C dipolar couplings. In particular, a nearly threefold increase in motional amplitudes of the backbone librations about C‐C α or N‐C α bonds was found on increasing the added water content up to 47 wt%D 2 O. On the basis of the frequencies of NMR observables involved, the timescale of the protein motions dependent on the added water content is estimated to be of the order of microseconds. This estimate agrees with that from wideline T 2 1 H NMR measurements. Also, our wideline 1 H NMR measurements revealed that the timescale of the microsecond motions in proteins reduces significantly on increasing the added water content, i.e., an ∼15‐fold increase in protein motional frequencies is observed on increasing the added water content to 45 wt% D 2 O. The observed changes in collagen dynamics is attributed to the increase in water translational diffusion on increasing the amount of added water, which leads to more frequent “bound water/free water” exchange on the protein surface, accompanied by the breakage and formation of new hydrogen bonds with polar functionalities of protein. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 246–256, 2014.