1H NMR studies of hydroxy protons of the V[β-Gal(1→3)-α-GalNAc(1→O)]THPGY glycopeptide

The hydroxy protons of the disaccharide moiety in the glycopeptide Val-[β-Gal(1→3)-α-GalNAc(1→O)]-Thr-His-Pro-Gly-Tyr (1) have been investigated in aqueous solution using 1H NMR spectroscopy. The chemical shifts (δ), coupling constants (3JCH,OH), temperature coefficients (dδ/dT), exchange rates (kex), and NOEs have been measured. The data show that the O(2′)H of Gal has a reduced contact with water due to steric interference caused by the 2-acetamido group of GalNAc. No interaction, in terms of hydrogen bonding exists between the disaccharide and the peptide moieties, but the rotation around the sugar-peptide linkage is restricted.