Stereospecific NMR assignments of prochiral methyls, rotameric states and dynamics of valine residues in malate synthase G.

Near complete stereospecific assignments of the prochiral methyl carbons of Leu and Val residues in malate synthase G, a 723 residue enzyme, are reported. Assignments were obtained on the basis of a 10% fractional (13)C-labeling strategy developed by Wüthrich and co-workers [Neri, D; Szyperski, T; Otting, G; Senn, H; Wüthrich, K. Biochemistry 1989, 28, 7510-7516] and, in the case of Val residues, supplemented with results from a series of new methyl-TROSY quantitative J experiments for measuring (3)J(C)(gamma)(N) and (3)J(C)(gamma)(C)' couplings. The measured (3)J couplings were also used to probe Val side chain dynamics. A strong correlation is observed between rotamer averaging established on the basis of the couplings and side chain millisecond time scale dynamics measured using methyl-TROSY based (1)H-(13)C multiple quantum relaxation dispersion experiments.