One- and two-dimensional 13C-n.m.r. characterization of two series of oligosaccharides derived from porcine intestinal mucosal heparin by degradation with heparinase

Abstract

Two tetrasaccharides, two hexasaccharides, and a disaccharide have been purified from heparinase digests of porcine intestinal mucosal heparin in sufficient quantities to permit 13C-n.m.r. characterization of the species. The two tetrasacchrides are the sulfated iduronic acid-containing 4en-Hex pA2SO 3-(1→4)-α- d-Glc pNSO 3;6SO 3-(1→4)-α- l-Ido pA2SO 3-(1→4)- d-Glc pNSO 3;6SO 3 and the non-sulfated glucuronic acid-containing 4en-Hex pA2SO 3-(1→4)-α- d-Glc pNSO 3;6SO 3-(1→4)-β- d-Glc pA-(1→4)- d-Glc pNSO 3;6SO 3. The two hexasaccharides are related to the two tetrasaccharides by the insertion of α-linked l-Ido pA2SO 3-(1→4)- d-Glc pNSO 3;6SO 3 after the non-reducing end sulfated glucosamine residue. The disaccharide is 4en-Hex pA2SO 3-(1→4)-α- d-Glc pNSO 3;6SO 3. The disaccharide, together with each of the iduronate-containing oligosaccharides, form one series of related di-, tetra-, and hexa-saccharides, while the disaccharide together with the glucuronate-containing oligosaccharides form a second series. Using inverse detection as a means of increasing sensitivity, two-dimensional n.m.r. 13C 1H heterocorrelation spectra have been obtained for all five oligosaccharides. The use of two-dimensional heterocorrelation n.m.r. spectroscopy offers a much less ambiguous means of making 13C resonance assignments than do traditional one-dimensional methods, while the use of inverse detection gives both greater sensitivity than direct detection, as well as values for the one-bond 13 1H coupling constants. From a knowledge of the assignments of resonances in the 1H spectra of these species, it has been possible to assign almost all of the 13C resonances of these five oligosaccharides. Some corrections to previously published assignments for the tetrasaccharides have been made. In addition, one-bond 13C 1H coupling constant data have been obtained for all of the anomeric protons.