Characterization of oligosaccharides from the chondroitin/dermatan sulfates - H-1-NMR and C-13-NMR studies of reduced trisaccharides and hexasaccharides

摘要

Chondroitin and dermatan sulfate (CS and DS) chains were isolated from bovine tracheal cartilage and pig intestinal mucosal preparations and fragmented by enzymatic methods. The oligosaccharides studied include a disaccharide and hexasaccharides from chondroitin ABC lyase digestion as well as trisaccharides already present in some commercial preparations. In addition, other trisaccharides were generated from tetrasaccharides by chemical removal of nonreducing terminal residues. Their structures were examined by high-field H-1 and C-13 NMR spectroscopy, after reduction using sodium borohydride. The main hexasaccharide isolated from pig intestinal mucosal DS was found to be fully 4-O-sulfated and have the structure: Delta UA(beta 1-3)GalNAc4S(beta 1-4)L-IdoA(alpha 1-3)GalNAc4S(beta 1-4)L-IdoA(alpha 1-3)GalNAc4S-ol, whereas one from bovine tracheal cartilage CS comprised only 6-O-sulfated residues and had the structure: Delta UA(beta 1-3) GalNAc6S(beta 1-4)GlcA(beta 1-3)GalNAc6S(beta 1-4)GlcA(beta 1-3)GalNAc6S-ol. No oligosaccharide showed any uronic acid 2-sulfation. One novel disaccharide was examined and found to have the structure: GalNAc6S(beta 1-4) GlcA-ol. The trisaccharides isolated from the CS/DS chains were found to have the structures: Delta UA(beta 1-3)GalNAc4S(beta 1-4)GlcA-ol and Delta UA(beta 1-3)GalNAc6S(beta 1-4)GlcA-ol. Such oligosaccharides were found in commercial CS/DS preparations and may derive from endogenous glucuronidase and other enzymatic activity. Chemically generated trisaccharides were confirmed as models of the CS/DS chain caps and included: GalNAc6S(beta 1-4)GlcA(beta 1-3)GalNAc4S-ol and GalNAc6S(beta 1-4) GlcA(beta 1-3)GalNAc6S-ol. The full assignment of all signals in the NMR spectra are given, and these data permit the further characterization of CS/DS chains and their nonreducing capping structures.