Urinary glycosaminoglycans bearing glucuronic acid or iduronic acid residue at the reducing terminals.

The urinary glycosaminoglycan was reduced with NaB[3H]4, and was separated into three fractions according to molecular size by column chromatography on Sephadex G-200. The hexuronic acid residues at the reducing terminals of each fraction were quantified by the method of preferential quantitation of hexuronic acid at the reducing terminals. This method consisted of hydrolysis with trifluoroacetic acid and nitrous acid, lactonization, and paper chromatographic analysis. Both radioactive gulonolactone and idonolactone were detected in the fractions with a lower molecular size, but not in those with a higher molecular size. These observations demonstrated that the glucuronide and iduronide linkages at other-than-terminal sites of carbohydrate chains were cleaved by the processes of depolymerization of glycosaminoglycans in tissues. Therefore, it is highly likely that endo-beta-glucuronidase(s) and endo-alpha-iduronidase(s) which belong to the glycosidase of endo type such as hyaluronidase are involved in the catabolic degradation of glycosaminoglycans in tissues.