The amide proton NMR chemical shift and hydrogen-bonded structure of peptides and polypeptides in the solid state as studied by high-frequency solid-state 1H NMR

High-resolution 1H NMR spectra of glycine (Gly)-containing peptides and polypeptides in the solid state were measured at 800 MHz and at high-speed magic-angle-spinning (MAS) of 30 kHz to elucidate the relationship between the hydrogen-bond length and 1H NMR chemical shift to add to our previous experimental and theoretical findings that there is a relationship between the hydrogen-bond length and 13C, 15N and 17O chemical shifts of various kinds of amino acid residues of peptides and polypeptides in the solid state. From these experimental results, it is found that the 1H chemical shifts of Gly amide protons of Gly-containing peptides and polypeptides, for which the hydrogen-bond length between the nitrogen and oxygen atoms (RN…O) have already been determined by X-ray diffraction, move downfield with a decrease in RN…O. Theoretical calculations qualitatively explain these experimental results.