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)

Rapid microtiter plate-based colorimetric assays have been developed that allow the screening of large numbers of samples for the presence of inhibitors of alpha-glucosidase, alpha-amylase, and beta-galactosidase. The assays are particularly useful for screening large numbers of microbial culture filtrates.
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PMID:High-throughput microtiter plate-based chromogenic assays for glycosidase inhibitors. 834 2

We describe a reagent for measuring alpha-amylase (EC 3.2.1.1) activity in serum with use of a thexyldimethylsilyl ether of p-nitrophenyl-alpha-D-maltoheptaoside (SB7) as substrate. This substrate differs from Genzyme's benzylidene-blocked p-nitrophenylmaltoheptaoside substrate (B-PNPG7). The reagent, optimized for the characteristics of the silyl-blocked substrate, contains 4-(2-hydroxyethyl)-1-piperazineethane sulfonate buffer at pH 7.3, alpha-glucosidase (maltase; EC 3.2.1.20), and glucoamylase (EC 3.2.1.3). Comparison with Ciba Corning Diagnostics Corp.'s, amylase reagent with B-PNPG7 as substrate (x) yielded a regression equation of y = 1.20x-2.7 (r = 0.9997). The linear range exceeded amylase concentrations > 2500 U/L and total precision (CV) was 2.3% at an amylase concentration of 112 U/L with the Ciba Corning 550 Express analyzer. Reconstituted reagent is stable for 30 days at 5 degrees C and 7 days at ambient (18-25 degrees C) temperatures.
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PMID:Evaluation of silyl-blocked p-nitrophenylmaltoheptaoside as a substrate for alpha-amylase reagents. 841 32

Oolong tea extract (OTE) was found to inhibit the water-insoluble glucan-synthesizing enzyme, glucosyltransferase I (GTase-I), of Streptococcus sobrinus 6715. The GTase-inhibitory substance in the OTE was purified successive adsorption chromatography on Diaion HP-21 and HP-20 columns; this was followed by further purification by Sephadex LH-20 column chromatography. A major fraction that inhibited GTase activity (fraction OTF10) was obtained, and the chemical analysis of OTF10 indicated that it was a novel polymeric polyphenol compound that had a molecular weight of approximately 2,000 and differed from other tea polyphenols. Catechins and all other low-molecular-weight polyphenols except theaflavin derived from balck tea did not show significant GTase-inhibitory activities. It was found that OTE amd PTF10 markedly inhibit GTase-I and yeast alpha-glucosidase, but not salivary alpha-amylase. Various GTases purified from S. sobrinus and Streptococcus mutans were examined for inhibition by OTE and OTF10. It was determined that S. sobrinus GTase-I and S. mutans cell-free GTase synthesizing water-soluble glucan were most susceptible to the inhibitory action of OTF10, while S. sobrinus GTase-Sa and S. mutans cell-associated GTase were moderately inhibited; no inhibition of S. sobrinus GTase-Sb was observed. Inhibition of a specific GTase or specific GTases of mutants streptococci resulted in decreased adherence of the growing cells of these organisms. The inhibitory effect of OTF10 on cellular adherence was significantly stronger than that of OTE.
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PMID:Inhibitory effect of oolong tea polyphenols on glycosyltransferases of mutans Streptococci. 848 34

Attempts to detect inducible carbohydrate-degrading enzymes from C. albicans were performed using carbohydrate-restricted media. Although alpha-amylase (polysaccharide hydrolase) was not induced from media containing starch or dextrin, alpha-glucosidase (disaccharide hydrolase) was induced from maltose-containing medium. alpha-Glucosidase activity was detected from the intact cells in suspension and from the supernatant of both spheroplasted and mechanically broken cells, but not from the media. Enzyme activity in intact cells was pH independent and increased during logarithmic growth phase and in media containing lower concentrations of maltose. The addition of 5 mM 1-deoxynojirimycin, a competitive inhibitor of alpha-glucosidase, suppressed fungal growth by more than 50%. These results suggest that alpha-glucosidase activity is crucial for fungal growth in medium containing maltose as a sole carbon source.
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PMID:A carbohydrate-degrading enzyme from Candida albicans: correlation between alpha-glucosidase activity and fungal growth. 856 8

A putative alpha-glucosidase clone has been isolated from a cDNA library constructed from mRNA of barley aleurones treated with gibberellin A 3 (GA). The clone is 2752 bp in length and has an uninterrupted open reading frame encoding a polypeptide of 877 amino acids. A 680 amino acid region is 43% identical to human lysosomal alpha-glucosidase and other glycosyl hydrolases. In isolated aleurones, the levels of the corresponding mRNA increase strongly after the application of GA, similar to the pattern exhibited by low-pI alpha-amylase mRNA. High levels are also observed in the aleurone and scutellum after germination, while low levels are found in developing seeds. The genome contains a single form of this alpha-glucosidase gene and two additional sequences that may be related genes or pseudogenes.
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PMID:Molecular cloning and characterization of a gibberellin-inducible, putative alpha-glucosidase gene from barley. 861 48

The activity of pancreatic (alpha-amylase, protease, and lipase) and enteral (maltase, glycyl-L-leucine dipeptidase, monoglyceride lipase) was studied in the experiments on adult male Wistar rats weighting 350 +/- 35 g 1-3, 7, 10, 30, 60, and 90 days after injection of a single dose of 25 mg per 100 g body weight. Acute heliotrine intoxication (in a toxic hepatitis model) was shown to lead to a marked decrease in the activities of both pancreatic and intestinal enzymes. It is suggested that the changes may be associated with the direct action of heliotrine on the pancreas and small intestinal mucosa or with hepatic failure.
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PMID:[Enzymatic activity of the pancreas and small intestinal mucosa in modelling of toxic hepatitis by administration of heliotrine]. 870 May 93

The Bacillus sp. SAM1606 alpha-glucosidase with a broad substrate specificity is the only known alpha-glucosidase that can hydrolyze alpha,alpha'-trehalose efficiently. The enzyme exhibits a very high sequence similarity to the oligo-1,6-glucosidases (O16G) of Bacillus thermoglucosidasius and Bacillus cereus which cannot act on trehalose. These three enzymes share 80% identical residues within the conserved regions (CR), which have been suggested to be located near or at the active site of the alpha-amylase family enzymes. To identify by site-specific mutagenesis the critical residues that determine the broad substrate specificity of the SAM1606 enzyme we compared the CR sequences of these three glucosidases and selected five targets to be mutagenized in SAM1606 alpha-glucosidase, Met76, Arg81, Ala116, Gly273, and Thr342. These residues have been specifically replaced by in vitro mutagenesis with Asn, Ser, Val, Pro, and Asn, respectively, as in the Bacillus O16G. The 12 mutant enzymes with single and multiple substitutions were expressed and characterized kinetically. The results showed that the 5-fold mutation virtually abolished the affinity of the enzyme for alpha, alpha'-trehalose, whereas the specificity constant for the hydrolysis of isomaltose, a good substrate for both the SAM1606 enzyme and O16G, remained essentially unchanged upon the mutation. This loss in affinity for trehalose was critically governed by a Gly273 --> Pro substitution, whose effect was specifically enhanced by the Thr342 --> Asn substitution in the 5-fold and quadruple mutants. These results provide evidence for the differential roles of the amino acid residues in the CR in determining the substrate specificity of the alpha-glucosidase.
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PMID:Altering substrate specificity of Bacillus sp. SAM1606 alpha-glucosidase by comparative site-specific mutagenesis. 899 34

Amylolytic enzymes are only slightly inhibited by thermal treated alpha-glucans (10-15%). The addition of glycine to the thermolysis mixture produces no increase of the inhibition. The inhibition of the enzyme activity is probably caused by short-chain alpha-glucans that the secondary binding places of the active centre coat and therefore the hydrolysis is reduced. Glucoamylase and alpha-amylase are not inhibited by non-dialysed melanoidines from the reaction of D-glucose and glycine, but there is a strong inhibition of alpha-glucosidase by these melanoidines (up to 45%). Strongly coloured, low molecular compounds that are formed during the Maillard-reaction and are soluble in ethyl acetate cause no inhibition of Glucoamylase and alpha-amylase.
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PMID:[Degradation of Maillard reaction products by amylolytic enzymes. 3. Inhibition of glucoamylase, alpha-amylase and alpha-glucosidase by heat treated alpha-glucans and melanoidins]. 912 78

A. niger produced alpha-glucosidase, alpha-amylase and two forms of glucoamylase when grown in a liquid medium containing raw tapioca starch as the carbon source. The glucoamylases, which formed the dominant components of amylolytic activity manifested by the organism, were purified to homogeneity by ammonium sulfate precipitation, ion-exchange and two cycles of gel filtration chromatography. The purified enzymes, designated GA1 and GA2, a raw starch digesting glucoamylase, were found to have molar masses of 74 and 96 kDa and isoelectric points of 3.8 and 3.95, respectively. The enzymes were found to have pH optimum of 4.2 and 4.5 for GA1 and GA2, respectively, and were both stable in a pH range of 3.5-9.0. Both enzymes were thermophilic in nature with temperature optimum of 60 and 65 degrees C, respectively, and were stable for 1 h at temperatures of up to 60 degrees C. The kinetic parameters Km and V showed that with both enzymes the branched substrates, starch and amylopectin, were more efficiently hydrolyzed compared to amylose. GA2, the more active of the two glucoamylases produced, was approximately six to thirteen times more active towards raw starches compared to GA1.
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PMID:Purification and properties of two forms of glucoamylase from Aspergillus niger. 913 12

A cDNA encoding sugar beet alpha-glucosidase was cloned from a library constructed from mRNA of suspension-cultured cells. The cDNA, 3056 bp in length, had an open reading frame encoding a polypeptide of 913 amino acid residues with a molecular mass of 102,078 Da, included only one of four regions which were conserved in the alpha-amylase family of enzymes. The deduced amino acid sequence from the analysis of the cDNA contained the sequences of the proteolysis peptides and the active site region peptide of sugar beet alpha-glucosidase. The primary structure indicated relatively high homology in the range of 28.2 to 54.3% to those for other alpha-glucosidases. The highest homology was found in barley alpha-glucosidase.
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PMID:Cloning and sequencing of a cDNA encoding alpha-glucosidase from sugar beet. 917 65


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