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

A smooth membrane fraction of Aspergillus niger catalyzed the transfer of mannose from GDP-mannose to endogenous lipid and protein acceptors. The mannolipid was acidic, as judged by diethylaminoethyl-cellulose chromatography, and had a mobility similar to ficaprenyl phosphate on thin-layer chromatograms. Mannose transfer occurred optimally at pH 6.5 to 7.5 and required Mn(2+) for use of the protein as acceptor, but either Mn(2+) or Mg(2+) with the lipid as acceptor. Glycopeptides of the mannosylated protein ([(14)C]gly) and of an alpha-glucosidase (alpha-glu) secreted by the organism were produced by Pronase digestion and separation of the products on Sephadex G-25. Because ovalbumin has a carbohydrate composition similar to that of alpha-glu and because the carbohydrate structure of ovalbumin is known, ovalbumin glycopeptides (Ov) were similarly obtained and used as standards in determining carbohydrate structures. Oligosaccharide chains of [(14)C]gly, alpha-glu, and Ov were obtained by treatment of the respective glycopeptides with endo-beta-N-acetylglucosaminidase, reduction with NaBT(4), and concanavalin A-Sepharose chromatography. The (3)H-labeled oligosaccharides obtained were subjected to the following treatments: (i) digestion with alpha- and beta-mannosidases, (ii) Smith degradation, and (iii) acetolysis. Subsequently, changes in paper chromatographic mobilities were detected. Also, alpha-glu was permethylated, and the partially methylated alditol acetates were analyzed by gas-liquid chromatography. The resultant proposed structure shows that the oligosaccharide chain of alpha-glu is almost identical to that of an Ov chain, while [(14)C]gly has a structure which is probably the same as that of alpha-glu. It is suggested that the transferase(s) involved in [(14)C]gly synthesis in vitro may be responsible for glycosylation of secreted enzymes.
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PMID:Mannosyl transfer by membranes of Aspergillus niger: mannosylation of endogenous acceptors and partial analysis of the products. 3 49

Enzymes capable of hydrolyzing cell walls of Blastomyces dermatitidis and chemotypes I and II of Histoplasma capsulatum were prepared in the laboratory or obtained from commercial sources. They included chitinases, beta-1,3-glucanases, beta-1,6-glucanase, and Pronase. Monosaccharides and disaccharides of glucose released from the cell walls by the enzymes were determined qualitatively by paper and gas-liquid chromatography, and monosaccharides were quantitated by the latter technique as well. An enzyme system isolated from Streptomyces sp. containing both chitinase and glucanase released maximum amounts of glucose and N-acetylglucosamine from the cell walls of H. capsulatum chemotype I. A chitinase preparation, free of glucanase, from Serratia marcescens released only chitobiose and N-acetylglucosamine from chemotype I cell walls, but the total quantity of N-acetylglucosamine released was about 60% less than that released by the Streptomyces system. A beta-1,3-glucanase from Bacillus circulans hydrolyzed the cell walls of H. capsulatum chemotype I, but a beta-1,6-glucanase failed to release glucose from the same walls. Autolytic enzymes, viz., beta-1,3-glucanases and several glycosidases were detected as constitutive enzymes in both yeast and mycelial phases of B. dermatitidis and H. capsulatum chemotypes I and II. No difference in the amount of activity was found between cell sap and culture filtrate preparations. The beta-glucanases prepared from the Histoplasma and Blastomyces strains were active on the cell walls of the yeast phases of H. capsulatum chemotypes I and II, releasing laminaribiose and glucose, but were essentially inactive on the cell walls of B. dermatitidis. Chitinase, beta-1,6-glucanase, alpha-glucanase, and alpha-glucosidase activities were absent from these fungal enzyme preparations.
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PMID:Cell wall studies of Histoplasma capsulatum and Blastomyces dermatitidis using autologous and heterologous enzymes. 87 Apr 37

The alpha-glucosidase inhibitor bromoconduritol (6-bromo-3,4,5-trihydroxycyclohex-1-ene) inhibits trimming of the innermost glucose residue from the Glc3Man9GlcNAc2 precursor of high-mannose and complex oligosaccharides. This inhibition occurs both in intact cells and with a microsomal enzyme preparation. The formation of lipid-linked oligosaccharides was increased in glucosidase-inhibited cells. Inhibition of transfer of high-mannose oligosaccharides to protein was not observed. In bromoconduritol-treated virus-infected cells, trimming of mannose can occur despite incomplete removal of glucose. The glucosylated high-mannose oligosaccharides GlcMan9GlcNAc, GlcMan8GlcNAc, and GlcMan7GlcNAc were released from viral glycoproteins after digestion with Pronase and endo-beta-N-acetylglucosaminidase H. The formation of complex oligosaccharides was concomitantly inhibited. The release of infectious fowl plague virus particles (an influenza virus) was inhibited from bromoconduritol-treated infected chicken-embryo cells.
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PMID:Inhibition of formation of complex oligosaccharides by the glucosidase inhibitor bromoconduritol. 675 22

Phenolics in food and agricultural processing by-products exist in the soluble and insoluble-bound forms. The ability of selected enzymes in improving the extraction of insoluble-bound phenolics from the starting material (experiment I) or the residues containing insoluble-bound phenolics (experiment II) were evaluated. Pronase and Viscozyme improved the extraction of insoluble-bound phenolics as evaluated by total phenolic content, antioxidant potential as determined by ABTS and DPPH assays, and hydroxyl radical scavenging capacity, reducing power as well as evaluation of inhibition of alpha-glucosidase and lipase activities. Viscozyme released higher amounts of gallic acid, catechin, and prodelphinidin dimer A compared to Pronase treatment. Furthermore, p-coumaric and caffeic acids, as well as procyanidin dimer B, were extracted with Viscozyme but not with Pronase treatment. Solubility plays an important role in the bioavailability of phenolic compounds, hence this study may assist in better exploitation of phenolics from winemaking by-products as functional food ingredients and/or supplements.
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PMID:Enzyme-assisted extraction of phenolics from winemaking by-products: Antioxidant potential and inhibition of alpha-glucosidase and lipase activities. 2737 48