Spatially Selective Heteronuclear Multiple‐Quantum Coherence Spectroscopy for Biomolecular NMR Studies

Abstract

Spatially selective heteronuclear multiple‐quantum coherence (SS HMQC) NMR spectroscopy is developed for solution studies of proteins. Due to “time‐staggered” acquisitioning of free induction decays (FIDs) in different slices, SS HMQC allows one to use long delays for longitudinal nuclear spin relaxation at high repetition rates. To also achieve high intrinsic sensitivity, SS HMQC is implemented by combining a single spatially selective 1 H excitation pulse with nonselective 1 H 180° pulses. High‐quality spectra were obtained within 66 s for a 7.6 kDa uniformly 13 C, 15 N‐labeled protein, and within 45 and 90 s for, respectively, two proteins with molecular weights of 7.5 and 43 kDa, which were uniformly 2 H, 13 C, 15 N‐labeled, except for having protonated methyl groups of isoleucine, leucine and valine residues. Expect longer delays: Spatially selective (SS) HMQC NMR spectroscopy is presented for solution studies of proteins. Using SS HMQC allows one to employ long delays for longitudinal nuclear spin relaxation at high repetition rates for acquisition of free induction decays. This technique is applied to uniformly 13 C, 15 N‐labeled and uniformly 2 H, 13 C, 15 N‐labeled (but methyl group protonated) proteins with molecular weights of 7.5 and 43 kDa.