Gradient- and sensitivity-enhanced heteronuclear multiple-quantum correlation spectroscopy.

A gradient- and sensitivity-enhanced HMQC experiment has been developed. The sensitivity of the experiment is increased by factors of the square root of 2 and 2 over the conventional and gradient-enhanced HMQC experiments, respectively. This improvement is achieved by retaining both the x and the y magnetization components in the indirectly detected dimension. This experiment will be particularly useful in NMR studies of large biomolecules as the relaxation time of the multiple-quantum coherence is much longer than that of the single-quantum coherence in the slow motion limit.