13 CHD 2 â??CEST NMR spectroscopy provides an avenue for studies of conformational exchange in high molecular weight proteins

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13 CHD 2 â??CEST NMR spectroscopy provides an avenue for studies of conformational exchange in high molecular weight proteins

Abstract

An NMR experiment for quantifying slow (millisecond) time-scale exchange processes involving the interconversion between visible ground state and invisible, conformationally excited state conformers is presented. The approach exploits chemical exchange saturation transfer (CEST) and makes use of 13CHD2 methyl group probes that can be readily incorporated into otherwise highly deuterated proteins. The methodology is validated with an application to a G48A Fyn SH3 domain that exchanges between a folded conformation and a sparsely populated and transiently formed unfolded ensemble. Experiments on a number of different protein systems, including a 360Â*kDa half-proteasome, establish that the sensitivity of this 13CHD2 13Câ??CEST technique can be upwards of a factor of 5 times higher than for a previously published 13CH3 13Câ??CEST approach (Bouvignies and Kay in J Biomol NMR 53:303â??310, 2012), suggesting that the methodology will be powerful for studies of conformational exchange in high molecular weight proteins.



Source: Journal of Biomolecular NMR