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)

An extracecular alpha-glucosidase (alpha-D-glucoside glycohydrolase, EC 3.2.1.20) of a thermophile, Bacillus thermoglucosidius KP 1006, was purified about 350-fold. The purified enzyme had a specific activity of 164 mumol of p-nitrophenyl-alpha-D-glucopyranoside hydrolyzed per min at 60 degrees C and pH 6.8 per mg of protein. The molecular weight was estimated at 55 000. The pH and temperature optima for activity were 5.0--6.0 and 75 degrees C, respectively. Below 40 degrees C, the activity was less than 4.5% of the optimym. The enzyme showed a high specificity for alpha-D-glucopyranoside. The maximal hydrolyzing velocity per substrate diminished in the order: phenyl-alpha-D-glucopyranoside, p-nitrophenyl-alpha-D-glucopyranoside, isomaltose, methyl-alpha-glycopyranoside. The respective Km values were 3.0, 0.23, 3.2 and 27 mM. The activity was trace for turanose, and not detectable for sucrose, trehalose, raffinose, melezitose, maltose, maltotriose, phenyl-alpha-D-maltoside, dextran, dextrin and starch. Tris, p-nitrophenyl-alpha-D-xylopyranoside, glucose and glucono-delta-lactone blocked competitively the enzyme with respect to p-nitrophenyl-alpha-D-glucopyranoside. The Ki values were 0.12, 0.14, 2.2 and 2.4 mM, respectively. The activity was affected by heavy metal ions, but insensitive to EDTA, p-chloromercuribenzoate and iodoacetate. The enzyme was stable up to 60 degrees C, and inactivated rapidly at temperatures beyond 72 degrees C. The pH range for stability was 4.0--11.0 at 31 degrees C, and 6.0--8.5 at 55.5 degrees C. At 25 degrees C, the enzyme failed to be inactivated in 45% ethanol, in 7.2 M urea, and in 0.06% sodium dodecyl sulfate, but the tolerance was extremely reduced at 60 degrees C.
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PMID:Purification and properties of extracellular alpha-glucosidase of a thermophile, Bacillus thermoglucosidus KP 1006. 0 45

Hitherto, seminal plasma maltase has been measured with maltose as substrate; this method is time consuming and lacks specificity. The use of a synthetic substrate, p-nitrophenol-alpha-D-glucopyranoside, allows accurate and rapid determination of this activity. When maltase is added to the incubation medium (the substrate and reduced glutathione in potassium phosphate buffer, pH 6.8), maintained at 37 degrees C, hydrolysis of the original substrate to p-nitrophenol goes at a constant rate during 4 h. Under optimal conditions of incubation, the Michaelis constant of the reaction, calculated by the Hanes method, was 2.92 +/- 0.84 (SD) X 10(-3) for six different semen samples. Isomaltase appeared to be absent from seminal plasma. The enzyme is stable to freezing and slow thawing and can be stored for at least 26 days at -80 degrees C. Its molecular weight is 259 000. Tris(hydroxymethyl)aminomethane (pH 6.8) exerts a noncompetitive inhibition on the enzyme activity. In 68 men 23 to 45 years old, whose semen analyses were normal, the seminal plasma maltase activity was 467 +/- 135 (SD) mU/g of protein. It was generally decreased in patients with infertility disorders.
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PMID:P-Nitrophenol-alpha-D-glucopyranoside as substrate for measurement of maltase activity in human semen. 2 9

Portions of closed jejunal biopsies from the dog were homogenised and their organelles separated by isopycnic centrifugation on continuous sucrose density gradients. The distributions of marker enzymes for the principal organelles were determined using highly sensitive assay procedures. The following organelles, with assayed marker enzymes and modal densities between brackets were characterised: peroxisomes (catalase, 1.21); brush borders (zinc-resistant alpha-glucosidase, leucyl-beta-naphthyl-amidase, gamma-glutamyl transferase, alkaline phosphatase, 1.20); lysosomes (N-acetyl-beta-glucosaminidase, alpha-mannosidase, 1.19); mitochondria (malate dehydrogenase, 1.18); endoplasmic reticulum (Tris-resistant alpha-glucosidase, 1.16); basal-lateral membranes (5'-nucleotidase, 1.11) and cytosol (lactate dehydrogenase). Homogenisation in isotonic sucrose containing digitonin (0.12 mmol/litre) selectively disrupted lysosomes and increased the equilibrium density of brush border and basal-lateral membranes. This procedure will be used to study the subcellular pathology of naturally occurring intestinal disease in the dog.
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PMID:Subcellular fractionation studies on peroral jejunal biopsies from the dog. 3 Jan 25

The alpha-glucosidase (alpha-D-glucoside glucohydrolase, EC 3.2.1.20) of Pseudomonas fluorescens W was partially purified by (NH4)2SO4 fractionation, Sephadex G-200 and DEAE-cellulose column chromatography. The enzyme showed great specificity for maltose hydrolysis, with very little action against polymeric forms. Sucrose, isomaltose, alpha-methylglucoside, and maltobionic acid were not hydrolyzed. Turanose was a strong competitive inhibitor, and glucose a weaker one. Tris (2-amino-2-hydroxymethylpropan-1:3-diol) inhibited enzyme activity significantly only at alkaline pH. Mercuric, cupric, and silver cations strongly inhibited, and EDTA (ethylenediaminetetraacetate) weakly inhibited the enzyme. The isolated enzyme was rather unstable even at 4 degrees C, and was destroyed by freezing and lyophilization. Inositol and albumin had a slightly protective effect. Sulfhydryl-binding reagents strongly inhibited the enzyme.
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PMID:Partial purification and characterization of alpha-glucosidase from Pseudomonas fluorescens W. 81 70

Calf pancreas microsomes incorporated radioactively labeled D-glucose from UDP-D-glucose into products extracted with chloroform/methanol (2:1, v/v), chloroform/methanol/water (10:102.5, v/v), and into the residual precipitate, with a pH optimum in Tris/maleate buffer of about 5.3. The chloroform/methanol extract contained a single 14C-labeled acidic product, which was identified as dolichyl beta-D-glucosyl phosphate. It was stable to mild alkali, yielded D-[14C]glucose upon mild acid hydrolysis, and a 14C-labeled compound with the chromatographic mobility of 1,6-anhydro-beta-D-glucopyranosyl upon hot alkali treatment. The [14C]glucolipid had the same chromatographic mobility as dolichyl beta-D-[14C]mannosyl phosphate, and its formation was stimulated by exogenous dolichyl phosphate. The chloroform/methanol/water extract contained radioactive lipid-bound oligosaccharides which were retained on DEAE-cellulose more strongly than dolichyl D-[14C]glucosyl phosphate. They were stable to mild alkali, but labile to acid and hot alkali. Acid treatment yielded a D-glucose-labeled oligosaccharide fraction which was shown by gel filtration to be slightly larger than most of the D-mannose-labeled oligosaccharides. About 80% of the radioactive D-glucose residues could be removed with alpha-glucosidase, but not with beta-glucosidase. Pancreatic dolichyl beta-D-[14C]glucosyl phosphate incubated with calf pancreas microsomes served as direct donor of D-glucosyl residues to lipid-bound oligosaccharides and to the precipitate. These oligosaccharides had the same size as those labeled from UDP-D-[14C]glucose, and the D-[14C]glucose residues could also be removed with alpha-glucosidase.
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PMID:Glucosyltransferase activity in calf pancreas microsomes. Formation of dolichyl D[14C]glucosyl phosphate and 14C-labeled lipid-linked oligosaccharides from UDP-D-[14C]glucose. 84 29

About 90% of the protein of hamster intestinal brush borders was solubilised in 0.25% (w/v) sodium dodecyl sulphate without total loss of biological activity. Detergent-polyacrylamide gel electrophoresis of the solubilised proteins separated 10-15 bands and partially resolved maltase, lactase, sucrase-maltase, trehalase and alkaline phosphatase activities. The disaccharidases, which were associated with the higher molecular weight proteins, were preferentially solubilised with 0.1%. (w/v) Triton X-100, butanol or papain, whereas Tris and NaI extracted only the lower molecular weight proteins, possible derived from the core filaments. Electrophoresis of brush border proteins metabolically labelled with [14-C] glucosamine suggested that many of the membrane-bound enzymes are glycoproteins. However, chromatography of a papain digest on Sephadex G-200 showed that the sucrase-maltase complex can be separated nearly free of carbohydrate without total loss of activity. The importance of characterizing membrane proteins solubilised by a number of techniques is discussed.
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PMID:Solubilization of brush borders of hamster small intestine and fractionation of some of the components. 113 70

In an attempt to detect acid maltase deficiency in neutrophils from patients with type II glycogenosis, without interference from the 'renal' alpha-glucosidase activity present in these cells, we have evaluated the contribution of the renal component in the total activity measured at pH 4.0 in extracts of human neutrophils. The renal contribution is about 13-25% and renal glucosidase appears to be closely related to the enzyme present on the epithelium of small intestine, which is known to be inhibited by Tris. We have used this compound as a selective inhibitor of the renal component of alpha-glucosidase activity measured at pH 4.0 in total extracts of neutrophils. Our results demonstrate that 0.1 mol/L Tris is an inhibitor of the renal alpha-glucosidase present in neutrophils and can be used to reduce the interference from this enzyme in assays of acid maltase.
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PMID:Tris discriminates between the different alpha-glucosidase activities from extracts of human neutrophils. 152 88

Using different conditions for incubation and fluorometry with 4-methylumbelliferylglycosides as substrates, we demonstrated the presence of acid alpha-glucosidase, "renal" alpha-glucosidase, N-acetyl-beta-D-glucosaminidase A, and N-acetyl-beta-D-glucosaminidase B in freshly drawn normal human serum. The acid alpha-glucosidase enzymatic activity was determined at pH 4.0 in 0.1 mol/L Tris reagent, whereas the renal isoenzyme activity was determined at pH 5.6 in presence of 0.05 mol/L turanose reagent. N-Acetyl-beta-D-glucosaminidases A and B were determined by their different behaviors on heating. The corresponding reference intervals for each enzyme were calculated from results for 40 controls: acid alpha-glucosidase (0.024 +/- 0.010 U/L), renal alpha-glucosidase (0.035 +/- 0.012 U/L), N-acetyl-beta-D-glucosaminidase A (10.2 +/- 2.9 U/L), and N-acetyl-beta-D-glucosaminidase B (4.4 +/- 2.1 U/L).
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PMID:alpha-Glucosidase and N-acetyl-beta-D-glucosaminidase isoenzymes in serum. 154 Oct 4

To clarify the enzyme participates in maltotriose synthesis, we purified maltase from rabbit kidney using 2-amino-2-hydroxymethylpropane-1,3-diol (Tris) affinity column chromatography. The purified enzyme possessed specific activity of 33.7 mumol/mg/min and estimated molecular weight of 350,000 dalton, as judged by SDS-polyacrylamide gel electrophoresis, comparable with those reported from rat kidney. Moreover this enzyme possessed not only maltase (maltose----glucose) but also amylomaltase (maltose----maltotriose) activity, and both activities were inhibited by Tris in a dose-dependent manner with similar IC50 values. From these results, we concluded that maltotriose was synthesized by maltase in vitro and that kidney maltase may participate in sugar metabolism in vivo.
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PMID:Synthesis of maltotriose by maltase purified from rabbit kidney. 177 60

A detergent solubilised sucrase from monkey small intestine has been purified 388-fold to gel electrophoretic homogeneity with an overall recovery of 36%. The molecular weight of the enzyme was 263 kDa by gel filtration. Electrophoresis in the presence of SDS indicates that the enzyme is a hetero-dimer. Mixed substrate inhibition studies and inhibition by PCMB and Tris suggest the presence of two catalytically active sites in the form of maltase and sucrase with isomaltase activity being common to both sites. Polyclonal antiserum against the purified enzyme showed a single continuous precipitin line with the purified antigen.
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PMID:Some properties of monkey intestinal sucrase. 211 33


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