Carbonyl 13C-detect solution-state protein NMR experiments to circumvent amide-solvent exchange broadening: Application to β2-microglobulin

Abstract

The 15N–1H heteronuclear single-quantum correlation (HSQC) technique in protein NMR spectroscopy suffers from line-broadening effects, such as chemical exchange of labile protons with solvent, and exchange broadening for residues undergoing conformational dynamics.The amide resonance of β2-microglobulin residue S88 is not observed in the HSQC spectrum but can be obtained through 13C-detect experiments that circumvent the problem of amide-solvent exchange broadening.Line broadening of S88 resonance beyond detection in the HSQC spectrum is not attributed to conformational exchange but rather to solvent exchange occurring on the order of ~103 s−1.