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Site‐Resolved Backbone and Side‐Chain Intermediate Dynamics in a Carbohydrate‐Binding Module Protein Studied by Magic‐Angle Spinning NMR Spectroscopy
Author(s) -
IvanirDabora Hadar,
Nimerovsky Evgeny,
Madhu P. K.,
Goldbourt Amir
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201500856
Subject(s) - side chain , magic angle spinning , nuclear magnetic resonance spectroscopy , crystallography , magnetic dipole–dipole interaction , solid state nuclear magnetic resonance , chemistry , molecular dynamics , residual dipolar coupling , molecule , spectroscopy , chemical shift , residue (chemistry) , magic angle , dipole , chemical physics , stereochemistry , nuclear magnetic resonance , computational chemistry , physics , organic chemistry , quantum mechanics , polymer
Magic‐angle spinning solid‐state NMR spectroscopy has been applied to study the dynamics of CBM3b–Cbh9A from Clostridium thermocellum ( ct CBM3b), a cellulose binding module protein. This 146‐residue protein has a nine‐stranded β‐sandwich fold, in which 35 % of the residues are in the β‐sheet and the remainder are composed of loops and turns. Dynamically averaged 1 H‐ 13 C dipolar coupling order parameters were extracted in a site‐specific manner by using a pseudo‐three‐dimensional constant‐time recoupled separated‐local‐field experiment (dipolar‐chemical shift correlation experiment; DIPSHIFT). The backbone‐Cα and Cβ order parameters indicate that the majority of the protein, including turns, is rigid despite having a high content of loops; this suggests that restricted motions of the turns stabilize the loops and create a rigid structure. Water molecules, located in the crystalline interface between protein units, induce an increased dynamics of the interface residues thereby lubricating crystal water‐mediated contacts, whereas other crystal contacts remain rigid.