Reducing terminals and molecular weights of glycosaminoglycans in normal human urine

To elucidate the reducing terminals and the molecular weights of urinary glycosaminoglycans (GAG), the reducing power of the GAG in the acidic subfractions obtained in a previous paper (Endo et al. 1980a) was determined by the methods of Park and Johnson and of Milner and Avigard. Number-average molecular weight was calculated from the value obtained by the Park-Johnson method according to the equation of Partridge et al. The results suggested that xylose and hexuronic acid were present at the reducing terminals of the carbohydrate chains of urinary GAG, and also that 10-65% of the reducing terminals were occupied by the hexuronic acid residues. This finding strongly suggested the exertion of endoglucuronidase activity in the catabolism of the tissue GAG, specifically of chondroitin sulfate isomers. On the other hand, number-average molecular weights of urinary GAG in the subfractions ranged from 5,600 to 15,500, although most of them were within the range between 6,000 and 7,500.