A STUDY OF PROTEIN SIDE-CHAIN DYNAMICS FROM NEW H-2 AUTOCORRELATION AND C-13 CROSS-CORRELATION NMR EXPERIMENTS - APPLICATION TO THE N-TERMINAL SH3 DOMAIN FROM DRK

Two new NMR experiments are presented for measuring side-chain dynamic s in proteins. The first method, requiring N-15, C-13, similar to 50% H-2-labeled protein, measures H-2 T-1 and T-1 rho spin relaxation time s at side-chain positions. A second experiment permits the straightfor ward measurement of C-13-H-1 dipole-dipole cross-correlation relaxatio n rates at C-13(beta) positions in N-15, C-13-labeled molecules. An ex cellent correlation is observed between order parameters, describing t he amplitude of motion at these sites, obtained on the basis of 2H rel axation and dipole-dipole cross-correlation relaxation rates. Together these experiments provide a powerful approach for selecting appropria te motional models. The methods are applied to study the side-chain mo tional properties of the N-terminal SH3 domain from the signaling prot ein drk. (C) 1998 Academic Press Limited.