PURE ABSORPTION PHASE GRADIENT-ENHANCED HMQC-TOCSY WITH DIRECT RESPONSE EDITING

Pulsed field gradients (PFG) have the potential to revolutionize furth er potent, inverse-detected structural NMR techniques by eliminating a rtifacts and thermal noise in data taken with very small numbers of tr ansients. A phase-sensitive GE (gradient-enhanced)-HMQC-TOCSY experime nt is reported with features which allow the discrimination (or elimin ation) of direct correlations relative to the relayed TOCSY responses, Sensitivity losses which arise from molecular diffusion during the co urse of a pulse sequence are potentially serious when field gradients are employed fur solutions containing small molecules, By carefully co mbining phase cycling with relatively weak pulsed field gradients, it is possible both to maintain good sensitivity and to suppress complete ly t(1) noise in GE-HMQC-TOCSY data acquired with only two transients per t(1) increment.