The disaccharide repeating-units of heparan sulfate

Five disaccharides have been isolated after degradation of heparan sulfate by heparinase (heparin lyase) and heparitinase (heparan sulfate lyase) and are suggested to represent the repeating units of the polysaccharide. They all contain a 4,5-unsaturated uronic acid residue and are: (a) A trisulfated disaccharide that is apparently identical to a disaccharide repeating-unit of heparin; (b) a disulfated disaccharide that seems unique for heparan sulfate and contains 2-deoxy-2-sulfamidoglucose and uronic acid sulfate residues; (c) a nonsulfated disaccharide containing a 2-acetamido-2-deoxyglucose residue; (d) a monosulfated disaccharide containing a 2-acetamido-2-deoxyglucose sulfate residue; and (e) a monosulfated disaccharide containing a 2-deoxy-2-sulfamidoglucose residue. Yields of these disaccharides from different heparan sulfate fractions are discussed in relation to possible arrangements of these units in the intact polymer.