Enzymatic Degradation of Whale Cartilage Keratosulfate-III

The properties of a keratosulfate-degrading enzyme derived from an enteric bacterium was investigated. The enzyme activity was optimal between pH 5.0 and 6.0, and at about 50°C. The enzyme exhibited complete specificity for keratosulfate, and did not hydrolyze hyaluronic acid, chondroitin 4-sulfate and 6-sulfate or heparin. Several inorganic compounds such as sodium, potassium, magnesium and calcium chlorides and mucopolysaccharides such as chondroitin 6-sulfate and heparin had no significant effect on the enzyme activity in the range of concentrations tested. The MICHAELIS constant value for bovine cornea keratosulfate was 1.9 mg per ml. In order to see what type of glycosidic bond in keratosulfate is attacked by the enzyme, the degraded products of bovine cornea keratosulfate were isolated by Sephadex filtration, and their structures were determined by means of chemical analysis, sodium borohydride reduction and the enzymatic treatment with β-N-acetylglucosaminidase. Judging from the results, the products were di-, tetrasaccharides and larger oligosaccharides, which had a galactose moiety on their reducing ends. Thus, it was concluded that this enzyme is an endo.poly-β-galactosidase.