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.
Shiono
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Department of Ophthalmology, Tohoku University School of Medicine, Miyagi, Japan.
D000818:Animals; D002417:Cattle; D004848:Epithelium / Q000201:enzymology; D006867:Hydrolases / Q000378:metabolism*; D007904:Lens Cortex, Crystalline / Q000201:enzymology; D007907:Lens Nucleus, Crystalline / Q000201:enzymology; D007908:Lens, Crystalline / Q000201:enzymology*; D013347:Subcellular Fractions / Q000201:enzymology
D006867:Hydrolases