Measuring (1)H (N) temperature coefficients in invisible protein states by relaxation dispersion NMR spectroscopy.
Measuring (1)H (N) temperature coefficients in invisible protein states by relaxation dispersion NMR spectroscopy.
J Biomol NMR. 2011 Mar 18;
Authors: Bouvignies G, Vallurupalli P, Cordes MH, Hansen DF, Kay LE
A method based on the Carr-Purcell-Meiboom-Gill relaxation dispersion experiment is presented for measuring the temperature coefficients of amide proton chemical shifts of low populated 'invisible' protein states that exchange with a 'visible' ground state on the millisecond time-scale. The utility of the approach is demonstrated with an application to an I58D mutant of the Pfl6 Cro protein that undergoes exchange between the native, folded state and a cold denatured, unfolded conformational ensemble that is populated at a level of 6% at 2.5°C. A wide distribution of amide temperature coefficients is measured for the unfolded state. The distribution is centered about -5.6*ppb/K, consistent with an absence of intra-molecular hydrogen bonds, on average. However, the large range of values (standard deviation of 2.1*ppb/K) strongly supports the notion that the unfolded state of the protein is not a true random coil polypeptide chain.
PMID: 21424227 [PubMed - as supplied by publisher]
Source:
PubMed