Study of protein dynamics in solution by measurement of (13)C (α)- (13)CO NOE and (13)CO longitudinal relaxation.

(13)C(α)-(13)CO homonuclear NOE and (13)CO T(1) relaxation were measured for a 20 kDa protein using tripleresonance pulse sequences. The experiments were sufficiently sensitive to obtain statistically significant differences in relaxation parameters over the molecule. The (13)C(α)-(13)CO cross-relaxation rate, obtained from these data, is directly proportional to an order parameter describing local motion and it is largely independent of the local correlation time. It is therefore a relatively straightforward observable for the identification of local dynamics.