Double- and zero-quantum NMR relaxation dispersion experiments sampling millisecond time scale dynamics in proteins

TROSY-based NMR relaxation dispersion experiments that measure the decay of double- and zero-quantum H-1-N-15 coherences as a function of applied H-1 and N-15 radio frequency (rf) fields are presented for studying millisecond dynamic processes in proteins. These experiments are complementary to existing approaches that measure dispersions of single-quantum N-15 and H-1 magnetization. When combined, data from all four coherences provide a more quantitative picture of dynamics, making it possible to distinguish, for example, between two-site and more complex exchange processes. In addition, a TFOSY-based pulse scheme is described for measuring the relaxation of amide H-1 single-quantum magnetization, obtained by a simple modification of the multiple-quantum experiments. The new methodology is applied to a point mutant of the Fyn SH3 domain that exchanges between folded and unfolded states at 25degreesC.