Characterization of partially purified alpha-glucosidase in the insoluble fraction of bovine crystalline lens.
Two fractions of neutral alpha-glucosidase were partially purified from the insoluble fraction of bovine lens. This is the first report of such an event to the best of our knowledge. The apparent native molecular weights of these fractions were 121 kDa (fraction-I) and 254 kDa (fraction-II). Both fractions contained three polypeptides with molecular weights of 21, 25 and 30 kDa, although the proportion of these peptides was different in both fractions. The optimal pH of fraction-I and fraction-II was pH 6.0 and 6.5, and the optimal temperature for both fractions was approximately 50 degrees C. The Km values of fractions-I and -II for 4-methylumbelliferyl-alpha-glucopyranoside were 0.086, and 0.192 mM. The activities of these enzymes were inhibited strongly by HgCl2 and slightly by D-iodoacetic acid, but not by D-turanose. From this, we suggest that the enzyme in the insoluble fraction of bovine lens may be a cytoplasmic neutral alpha-glucosidase which binds to the cell membrane.
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
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Kamei
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Fujiyama
D000818:Animals; D002384:Catalysis; D002417:Cattle; D002852:Chromatography, Ion Exchange; D003902:Detergents; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D065089:Glycoside Hydrolase Inhibitors; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007908:Lens, Crystalline / Q000201:enzymology*; D012995:Solubility; D013696:Temperature; D000520:alpha-Glucosidases / Q000302:isolation & purification / Q000378:metabolism* / Q000502:physiology
D003902:Detergents; D065089:Glycoside Hydrolase Inhibitors; D000520:alpha-Glucosidases