triple-resonance spectroscopy HNCA CHMO:0002557 Hils CHMO:0002058 A triple-resonance NMR experiment used in to determine the chemical shifts of nuclei in a (isotopically enriched) protein. The chemical shift of the (backbone) amide proton is correlated with the chemical shift of the covalently bound nitrogen and the alpha carbons of the same and preceding residues. HNCA experiment 2009-10-25T08:10:21Z