Acid hydrolases in the bovine lens epithelium

Acid hydrolases (acid phophatase, N-acetyl-beta-D-glucosaminidase, alpha-D-mannosidase, alpha-L-fucosidase, and beta-D-glucuronidase) in the bovine lens epithelium were studied biochemically. p-Nitrophenyl derivatives were used as substrate. All enzymatic activity was found to be much higher in the epithelium than in the cortex and nucleus. The properties of acid phosphatase, N-acetyl-beta-D-glucosaminidase, and alpha-D-mannosidase were also studied, yielding Km values of 0.28, 0.95, and 0.53 mM, respectively. The optimal pH of these enzymes was acidic. Among the subcellular fractions, both acid phosphatase and N-acetyl-beta-D-glucosaminidase had the highest enzymatic activities in the 20,000 g precipitate fraction, while alpha-D-mannosidase showed no difference in activity among the subcellular fractions, suggesting that alpha-D-mannosidase in the bovine lens epithelium is nonlysosomal.