THE SENSITIVITY OF EXPERIMENTS WHICH USE GRADIENT PULSES FOR COHERENCE-PATHWAY SELECTION

The use of field-gradient pulses for coherence selection in multidimen sional NMR experiments may cause a reduction in sensitivity per unit t ime when compared to experiments which use phase cycling. In addition, care must be taken to introduce the gradients in such a way as to ret ain the possibility of producing spectra with pure phase (i.e., absorp tion-mode lineshapes). The commonly used methods of implementing gradi ent pulses in multidimensional experiments are evaluated and compared with respect to these issues. These predictions are confirmed for a si mple molecular system. The experimentally achieved sensitivities are a lso compared, on a residue-by-residue basis, for the case of different nitrogen-15 proton HSQC spectra of a 166 residue protein. (C) 1994 Ac ademic Press, Inc.