Transverse relaxation optimised spin-state selective NMR experiments for measurement of residual dipolar couplings.

Three transverse relaxation optimised NMR experiments (TROSY) for the measurement of scalar and dipolar couplings suitable for proteins dissolved in aqueous iso- and anisotropic solutions are described. The triple-spin-state-selective experiments yield couplings between 1HN-13Calpha, 15N-13Calpha, 1HN-13Calpha(i-1), 15N-13Calpha(i-1), 1HN-13C'(i-1), 15N-13C'(i-1) and 13C'(i-1)-13Calpha(i-1) without introducing nonessential spectral crowding compared with an ordinary two-dimensional 15N-1H correlation spectrum and without requiring explicit knowledge of carbon assignments. This set of alpha/beta-J-TROSY experiments is most useful for perdeuterated proteins in studies of structure-activity relationships by NMR to observe, in addition to epitopes for ligands, also conformational changes induced by binding of ligands.