Beta-glycosidases and diabetic microangiopathy. II. An insulin-dependent isozyme of beta-N-acetylglucosaminidase.

Previously we reported that beta-glycosidase activities were markedly decreased in the kidney but increased in the serum of diabetic rats. To examine these changes, the isozymes of beta-N-acetylglucosaminidase [EC 3.2.1.30] of rats were examined by DEAE-cellulose column chromatography. At least 3 major isozymes were found in both the kidney and liver. The main isozyme was type II isozyme in normal rat kidney and type III in normal rat liver. The activity of the type II isozyme in the kidney was markedly lowered when the total activity was decreased in diabetes and its normal activity was restored on insulin treatment, in parallel with increase in the total activity in diabetes. No significant change was found in the chromatographic pattern of isozymes in the liver in diabetes. In diabetic rat serum, the increase of total activity was found to be due to increase of type I and II isozymes.