CORRELATING BACKBONE AMIDE AND SIDE-CHAIN RESONANCES IN LARGER PROTEINS BY MULTIPLE RELAYED TRIPLE RESONANCE NMR

A new three-dimensional triple resonance NMR experiment is described that correlates the amide H-1 and N-15 resonances of one residue simultaneously with both the C-13-alpha and C-13-beta resonances of its preceding residue. Sensitivity of the new experiment is comparable with that of the HN(CO)CA experiment (Bax, A.; Ikura, M. J. Biomol. NMR 1991, 1, 99-105), but the additional correlation to the C(beta) resonance of the preceding residue provides invaluable assignment information, previously inaccessible. The technique is demonstrated for interferon-gamma, a homodimeric protein of 31.4 kDa, enriched uniformly with C-13 and N-15.