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A high resolution 1 H magic angle spinning NMR study of a high‐ M r subunit of wheat glutenin
Author(s) -
Alberti Enrica,
Humpfer Eberhard,
Spraul Manfred,
Gilbert Simon M.,
Tatham Arthur S.,
Shewry Peter R.,
Gil Ana M.
Publication year - 2001
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(200101)58:1<33::aid-bip40>3.0.co;2-x
Subject(s) - chemistry , magic angle spinning , chemical shift , crystallography , nuclear magnetic resonance spectroscopy , resolution (logic) , polyproline helix , hydrogen bond , glutenin , protein subunit , high resolution , amide , molecule , stereochemistry , peptide , organic chemistry , biochemistry , artificial intelligence , computer science , gene , remote sensing , geology
This work describes the application of 1 H magic angle spinning (MAS) nmr to the study of hydrated 1Dx5 wheat high‐M r subunit. 1Dx5 is a water‐insoluble 88 kDa protein, associated with good baking performance, and whose structure in the solid and low‐hydration states is not known. High‐resolution MAS (HR‐MAS) results in a threefold resolution improvement of the 1 H spectra of the hydrated wheat protein, compared to standard MAS. The spectral resolution achieved enables, for the first time, two‐dimensional nmr methods to be employed for the study of hydrated 1Dx5 and the assignment of the spectrum to be carried out on the basis of total correlated spectroscopy and 13 C/ 1 H correlation experiments. Considerable shifts are observed for some resonances, relative to the chemical shifts of amino acids in solution, indicating that specific interactions occur in the hydrated protein network. Two main environments are identified for glutamine residues, Q 1 and Q 2 , and these were characterized in terms of possible conformation and relative dynamics, with the basis of comparison between the single 90° spectrum and the Carr‐Purcel‐Heiboom‐Gill (CPMG) spectrum. The Q 1 residues are proposed to be situated in protein segments that adopt the β‐sheet conformation and that remain relatively hindered, possibly by hydrogen bonds involving the glutamine amide groups. On the other hand, Q 2 residues are proposed to be situated in a more mobile environment, adopting a looser conformation, possibly a β‐turn conformation. Based on the proximity of the Q 2 residues with glycine residues, as viewed by the nuclear Overhauser effect spectroscopy experiment, it is proposed that the protein segments that form the more mobile (or loop) sections of the network are rich in both glutamine and glycine residues. © 2000 John Wiley & Sons, Inc. Biopoly 58: 33–45, 2001