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.