Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A sucrase from honey bees (Apis mellifera) which precipitates between ammonium sulfate saturations of 50 and 70% (5 mg protein per millilitre) and which makes up the major portion of the sucrases of honey bees was purified to homogeneity as shown by several criteria. A large part of the sucrase was found in the head while most of the rest was in the abdomen (a small amount was in the thorax). The enzyme precipitated between the same values of ammonium sulfate saturation as did the sucrase in honey and honey sucrase exhibited kinetics very similar to those of this enzyme. The enzyme was found to be a relatively nonspecific alpha-glucosidase and was shown to have transglucosidase activity. The production of glucose from sucrose was rectilinear when plotted by the Hofstee method at low substrate concentrations but decreased at high sucrose concentrations. The production of fructose was rectilinear throughout the concentration range used. The production of both glucose and rho-nitrophenol when rho nitrophenyl alpha-D-glucoside was the substrate was linear by the Hofstee plot. These effects were found to be due to transglucolysis and a mechanism of action is proposed. Amino acid and amino sugar analyses indicated that the sucrase was a glycoprotein. The molecular weight was found to be between 51000 and 82000 by three different methods and an so20.w value of 4.0 S was obtained. There was no evidence for subunit structure. Tests of the enzyme under various denaturation conditions did not reveal any unusual stabilities. The sucrase bound very tightly to a hydrophobic column. Iodoacetic acid decreased the activity of the sucrase but a large concentration was needed to bring about a 50% activity loss. Reducing agents caused some activity declines. Diethyl pyrocarbonate activated the enzyme.
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PMID:Physical, chemical, and enzymatic studies on the major sucrase of honey bees (Apis mellifera). 0 3

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.
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PMID:Characterization of partially purified alpha-glucosidase in the insoluble fraction of bovine crystalline lens. 853 10