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Long‐Lived States to Monitor Protein Unfolding by Proton NMR
Author(s) -
Bornet Aurélien,
Ahuja Puneet,
Sarkar Riddhiman,
Fernandes Laetitia,
Hadji Sonia,
Lee Shirley Y.,
Haririnia Aydin,
Fushman David,
Bodenhausen Geoffrey,
Vasos Paul R.
Publication year - 2011
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100365
Subject(s) - conformational isomerism , chemistry , relaxation (psychology) , proton , spins , crystallography , antisymmetric relation , ubiquitin , nuclear magnetic resonance , computational chemistry , molecule , physics , organic chemistry , condensed matter physics , biochemistry , psychology , quantum mechanics , mathematical physics , gene , social psychology
The relaxation of long‐lived states (LLS) corresponds to the slow return to statistical thermal equilibrium between symmetric and antisymmetric proton spin states. This process is remarkably sensitive to the presence of external spins and can be used to obtain information about partial unfolding of proteins. We detected the appearance of a destabilized conformer of ubiquitin when urea is added to the protein in its native state. This conformer shows increased mobility in the C‐terminus, which significantly extends the lifetimes of proton LLS magnetisation in Ser‐65. These changes could not be detected by conventional measurements of T 1 and T 2 relaxation times of protons, and would hardly be sensed by carbon‐13 or nitrogen‐15 relaxation measurements. Conformers with similar dynamic and structural features, as revealed by LLS relaxation times, could be observed, in the absence of urea, in two ubiquitin mutants, L67S and L69S.