HCCH-TOCSY spectroscopy of 13C-labeled proteins in H2O using heteronuclear cross-polarization and pulsed-field gradients.

A pulsed-field gradient-enhanced, heteronuclear cross-polarization-driven, 3D HCCH-TOCSY experiment is described, which in a single scan can achieve nearly ideal solvent suppression for protein samples in H2O solution. The 3D experiment can be transformed without additional pre- or post-processing, thus leaving solute resonances at the solvent resonance position undisturbed and easily identifiable. As the gradients are used in combination with a 13C z-filter, only minimal relaxation losses are encountered as compared to non-gradient versions.