13C-N.m.r.-spectral study of the mode of binding of Gd3+ to various glycopeptides.
Natural-abundance, 13C-n.m.r. spectroscopy was used to study the mode of binding of Gd3+ to mono-O-glycosylated L-serine and tripeptides variously composed of Gly and L-Thr. When the amino and carboxyl groups of the amino acid are not blocked, strong interaction of Gd3+ with them is observed; this is also readily apparent with some related, nonglycosylated peptides. When the amino and carboxyl groups of the amino acid are blocked, noticeable interaction of Gd3+ with the glycosidic oxygen atom (O-3) and O-2' for the glycopeptide containing alpha-D-Galp, and with O-3 and N-2' for the glycopeptide containing alpha-D-GalpNAc, is observed. Weak interactions are also possible with O-4' and O-6' of the glycosyl groups. Although the amino acids were protected, these metal ion-carbohydrate interactions may still be mediated, to some extent, by the acetyl protecting the amino group and by the ester group on the amino acid.
D005682:Gadolinium; D006020:Glycopeptides / Q000138:chemical synthesis; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D013329:Structure-Activity Relationship
D006020:Glycopeptides; D007202:Indicators and Reagents; D005682:Gadolinium