[1P-48(WS3-2)] A combinatorial acquisition of distinct protein NMR spectra based on multiplicity-dependent resonance editing
A procedure is presented for the substantial simplification of 2D constant-time 13C-1H heteronuclear single-quantum correlation (HSQC) spectra of 13C-enriched proteins. In this approach, a single pulse sequence simultaneously records eight sub-spectra wherein the phases of the NMR signals depend on spin topology. Signals from different chemical groups are then stratified into different sub-spectra through linear combination based on Hadamard encoding of 13CHn multiplicity (n = 1, 2, and 3) and the chemical nature of neighboring 13C nuclei (aliphatic, carbonyl/carboxyl, aromatic). This results in five sets of 2D NMR spectra containing mutually exclusive signals from: (i) 13Cβ-1Hβ correlations of Asn and Asp, 13Cγ-1Hγ correlations of Gln and Glu acid, and 13Cα-1Hα correlations of Gly, (ii) 13Cα-1Hα correlations of all residues but glycine, and (iii) 13Cβ-1Hβ correlations of Phe, Tyr, His, and Trp, and the remaining (iv) aliphatic 13CH2 and (v) aliphatic 13CH/13CH3 resonances. As HSQC is a common element of many NMR experiments, the spectral simplification proposed in this article can be straightforwardly implemented in experiments for resonance assignment and structure determination and should be of widespread utility.