Time-saving methods for heteronuclear multidimensional NMR of ((13)C, (15)N) doubly labeled proteins.

Heteronuclear 2D ((13)C, (1)H) and ((15)N, (1)H) correlation spectra of ((13)C, (15)N) fully enriched proteins can be acquired simultaneously with virtually no sensitivity loss or increase in artefact levels. Three pulse sequences are described, for 2D 'time-shared' or TS-HSQC, 2D TS-HMQC and 2D TS-HSMQC spectra, respectively. Independent spectral widths can be sampled for both heteronuclei. The sequences can be greatly improved by combining them with field-gradient methods. By applying the sequences to 3D and 4D NMR spectroscopy, considerable time savings can be obtained. The method is demonstrated for the 18 kDa HU protein.