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

Abstract

The urinary glycosaminoglycan was reduced with NaB [3H14, 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-f3-glucuronidase(s) and endo-a-iduronidase(s) which belong to the glycosidase of endo type such as hyaluronidase are involved in the catabolic degradation of glycosaminoglycans in tissues. reducing terminal ; urinary glycosaminoglycan ; glucuronic acid ; iduronic acid ; endo-glucuronidase Urinary glycosaminoglycans (GAGS) are metabolites of tissue proteoglycans which are catabolized by concerted actions of proteases, glycosidases and sulfatases in various tissues (Varadi et al. 1967;Constantopoulos et al. 1969; Wasteson and Wessler 1971; Endo et al. 1980a, b). Therefore, it is conceivable that detailed studies of human urinary GAGS provide important clues to the metabolism of tissue GAGS. Endo et al. (1980c) and Maj ima et al. (1984b) demonstrated the presence of