title: A 500-MHz proton-magnetic-resonance study of several fragments of the carbohydrate-protein linkage region commonly occurring in proteoglycans.
abstract: The proton-magnetic-resonance spectra of three partial structures of the carbohydrate-protein linkage region that frequently occurs in proteoglycans, namely, beta-D-Galp-(1 leads to 3)-beta-D-Galp-(1 leads to 4)-beta-D-Xylp-(1 leads to O)-L-Ser, were recorded in 2H2O at 500 MHz; they could be completely interpreted, both for the glyco-serines and for the corresponding glyco-xylitols. The chemical shifts and the coupling constants were refined by computer simulation of the spectra. The change in the chemical shift of H-4 of a D-galactopyranosyl residue upon substitution at C-3 by a beta-D-galactopyranosyl group is proposed to be characteristic for this particular attachment, making H-4 of galactose a structural-reporter group. The three constituting monosaccharides adopt the 4C1 (D) ring conformation. The terminal galactopyranosyl group and the internal galactopyranosyl residue differ as to the population of rotamers around the C-5/C-6 axis. Concomitantly, the flexibility of their glycosidic linkages is distinct.
mesh_terms: D002241:Carbohydrates / Q000032:analysis*; D055598:Chemical Phenomena; D002621:Chemistry; D009682:Magnetic Resonance Spectroscopy; D010446:Peptide Fragments / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D011509:Proteoglycans; D011522:Protons
chemical_list: D002241:Carbohydrates; D010446:Peptide Fragments; D011506:Proteins; D011509:Proteoglycans; D011522:Protons