A 4D HCC(CO)NNH EXPERIMENT FOR THE CORRELATION OF ALIPHATIC SIDE-CHAIN AND BACKBONE RESONANCES IN C-13/N-15 LABELED PROTEINS

We recently proposed a novel four-dimensional (4D) NMR strategy for the assignment of backbone nuclei in spectra of C-13/N-15-labelled proteins (Boucher et al. (1992) J. Am. Chem. Soc., 114, 2262-2264 and J. Biomol. NMR, 2, 631-637). In this paper we extend this approach with a new constant time 4D HCC(CO)NNH experiment that also correlates the chemical shifts of the aliphatic sidechain (H-1 and C-13) and backbone (H-1, C-13alpha, and N-15) nuclei. It separates the sidechain resonances, which may heavily overlap in spectra of proteins with large numbers of similar residues, according to the backbone nitrogen and amide proton chemical shifts. When used in conjunction with a 4D HCANNH or HNCAHA experiment it allows, in principle, complete assignment of aliphatic sidechain and backbone resonances with just two 4D NMR experiments.