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 p-nitrophenyl-alpha-D-glucopyranoside-hydrolyzing alpha-glucosidase from an obligate thermophile, Bacillus thermoglucosidius KP 1006, gave a triphasic relationship at pH 6.8 in the van't Hoff plot of Km, in the Arrhenius plot of the first order rate constant of inactivation with 0.1% sodium dodecyl sulfate, and in the logarithmic plot of the maximal fluorescence intensity at 346 nm versus reciprocal of temperature. The respective plots exhibited two breaks at 40 and 61 degrees C, 43 and 62 degrees C, and 40 and 61 degrees C. However, the Arrhenius plot of the molecular activity at pH 6.8 had a single discontinuity at 64 degrees C. These findings, together with thermodynamic quantities for the enzyme, suggest that the thermal conformation changes in the enzyme protein occur around 40--43 degrees C and 61--64 degrees C. The Arrhenius plot of the rate constant of heat inactivation at pH 6.8 was bent at 73 degrees C. Thermodynamic data indicate that the enzyme is transformed from a heat stable form into a heat unstable form at 73 degrees C with temperature elevation. The critical points localized near the minimum, optimum, and maximum temperatures (40, 60, and 72 degrees C) of the cell growth, respectively.
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PMID:Bacillus thermoglucosidius alpha-glucosidase. Temperature dependence of activity and stability. 699 50

Glucosidase activities capable of removing the three glucose residues from Glc3Man9GlcNAc2 oligosaccharide were detected in a cell-free preparation of Saccharomyces cerevisiae X-2180. The glucosidase which cleaves the glucose residue at the nonreducing terminus (Glc3Man9GlcNAc2 oligosaccharide glucosidase) was equally distributed between the particulate and the supernatant fractions obtained after centrifugation of the yeast homogenate at 27,000 X g for 30 min. The membrane-bound activity was stimulated by Triton X-100, whereas the supernatant activity was not affected. The soluble Glc3Man9GlcNAc2 oligosaccharide glucosidase was partially purified from the supernatant by ammonium sulfate fractionation followed by DEAE-Sephadex chromatography. It was clearly separated from alpha-glucosidase, which acts onp-nitrophenyl-alpha-D-glucopyranoside, but still contained beta-glucosidase and alpha-mannosidase acting on p-nitrophenyl-beta-D-glucopyranoside and alpha-D-mannopyranoside, respectively. The Glc3Man9GlcNAc2 oligosaccharide glucosidase had a pH optimum of 6.8, and showed no requirement for divalent cations. The enzyme was very active with glucose-labeled Glc3Man9GlcNAc2, was slightly active with Glc2Man9GlcNAc2, and showed no activity with Glc1Man9GlcNAc2. These properties suggest that this enzyme is involved in the first step of processing of oligosaccharides after transfer from dolichyl pyrophosphate to proteins.
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PMID:Partial purification from Saccharomyces cerevisiae of a soluble glucosidase which removes the terminal glucose from the oligosaccharide Glc3Man9GlcNAc2. 701 69

Cultivation of the yeast Pichia guilliermondii in a medium with a high content of sulfate or phosphate ions (0.6 M and higher) increased its susceptibility to actinomycin D and 7-methyl-8-trifluoromethyl 10-(1'-D-ribityl)isoalloxazin, and analog of riboflavin, and decreased the requirement of the riboflavin-dependent mutant P7 in exogenous vitamin B2. The protoplasts of the yeast were also very susceptible to actinomycin D when they were incubated in a medium with a high sulfate concentration. Sulfate and phosphate ions elevated the susceptibility to actinomycin D in the following yeasts, apart from P. guilliermondii: Pichia pinus, Saccharomyces cerevisiae, Torulopsis candida, hansenula polymorpha, Schwanniomyces occidentalis, Candida utilis and Candida tropicalis. The growth of Escherichia coli was also very susceptible to actinomycin D when the bacterium was cultivated in medium with an elevated phosphate concentration (0.2 M). High phosphate or sulfate concentrations can be used in experiments aimed at studying the effect of transcription inhibitors (actinomycin D, 8-hydroxyquinoline) on the induction of alpha-glucosidase in P. guilliermondii.
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PMID:[Increase in yeast and bacterial sensitivity to inhibitors and riboflavin as affected by high sulfate and phosphate concentrations]. 701 54

Purifications of mouse intestinal brush-border membranes from control explants and scrapings of intestinal mucosa have been compared. Based on the specific activity of sucrase used as a specific marker of these membranes, higher purification factors were obtained with control explants (24.7 +/- 0.9) as compared with scrapings of intestinal mucosa (14.8 +/- 0.9). However, similar patterns of proteins and enzymes were obtained by sodium dodecyl sulfate (SDS) - polyacrylamide gel electrophoresis after membrane solubilization by 2% SDS at room temperature. After 24 h of culture, higher molecular weight species of maltase-glucoamylase-isomaltase (band 4), alkaline phosphatase (bands 9-10), and trehalase (band 17) have been observed. Enzyme species appearing in the particulate fraction of culture media were, however, identical with those found at the brush-border membrane level in control explants, except for trehalase. These results are interpreted by considering the possible adsorption of serum components to brush-border membrane proteins. It thus appears that the membrane proteins and enzymes released in the media during organ culture are identical with those synthesized in the tissue in vitro or in vivo.
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PMID:Proteins and enzymes of the brush-border membrane of mouse intestine: influence of organ culture on gel electrophoretic patterns. 710 21

The hydroxylsine-linked disaccharide unit, 2-O-alpha-D-glucopyranosyl-O-beta-D-galactopyranosyl-hydroxylysine (Glc-Gal-Hyl), prepared from collagens, was hydrolyzed by a glucohydrolase present in rat spleens and lungs. This disaccharide unit was scarcely hydrolyzed by homogenates of intestines, livers, and kidneys, which had a high alpha-D-glucosidase activity for neutral glucosides. The Glc-Gal-Hyl glucohydrolase was purified from rat spleens by affinity chromatography and gel filtration to the extent that sodium dodecyl sulfate/polyacrylamide gel electrophoresis gave a single band stained by Coomassie blue G-250. This purified glucohydrolase had a pH optimum around 5.8, and the Michaelis constant was 5.9 mM when Glc-Gal-Hyl was used as a substrate. This enzyme did not hydrolyze neutral glucosides. It is concluded that this Glc-Gal-Hyl glucohydrolase is responsible for catabolism of the hydroxylsine-linked disaccharide unit derived from collagens in mammals.
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PMID:Enzymatic hydrolysis of disaccharide unit of collagen. Isolation of 2-O-alpha-D-glucopyranosyl-O-beta-D-galactopyranosyl-hydroxylysine glucohydrolase from rat spleens. 746 Sep 18

Membrane proteins can be attached to the plasma membrane in several ways. Recently, a mechanism has been described, by which a number of cell surface proteins are anchored to the exoplasmic side of the plasma membrane by covalent linkage to glycosyl-phosphatidylinositol (GPI). The growth properties of renal epithelial cells in tissue culture enable free access to apical cell surface and brush border membrane proteins. To study the nature of membrane anchoring of apical plasma membrane enzymes in cultured renal epithelial cells, confluent LLC-PK1, OK, NRK, and MDCK epithelia were treated in tissue culture dishes with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC), and the PI-PLC-specific release into the tissue culture medium of the apical membrane enzymes alkaline phosphatase (AP), gamma-glutamyl transpeptidase, leucine aminopeptidase, trehalase, and maltase was determined. Of the five enzymes tested, AP and trehalase, already described as GPI-anchored membrane proteins, were specifically released by PI-PLC from intact cell monolayers. Of the four cell lines investigated, LLC-PK1 cells express AP and trehalase which were released by PI-PLC. In OK cells, which lack AP activity, only trehalase was found to have PI-PLC-releaseable enzyme activity. MDCK cells, on the other hand, express AP activity, releaseable by PI-PLC, but no trehalase activity. In studies on the time course of synthesis and reinsertion of AP into the apical membrane of LLC-PK1 cells after removal by PI-PLC, a 60% recovery of AP activity was obtained only after 7 days. Analysis of protein release by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of culture supernatants after surface labeling with biotin and subsequent Western blotting with streptavidin revealed four protein bands at approximately 130, 90, 30, and 20 kD in LLC-PK1 cells and five GPI-anchored proteins at 110, 85, 65, 40, and 26 kD in OK cultures. The finding of a PI-PLC-specific release of apical membrane enzymes from renal tubular cell lines of different species (pig, opossum, rat, and dog) and of different nephron origin indicates a high conservation of the GPI anchor of renal brush border membrane proteins and further proves the high degree of differentiation retained by the cell lines in tissue culture. In addition, this method may provide a possible tool for isolating GPI-anchored apical membrane proteins from intact epithelial monolayer cultures.
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PMID:Selective release of apical membrane enzymes from cultured renal epithelia by phosphatidylinositol-specific phospholipase C. 750 39

Glycosidases and glycosyltransferases were electrophoresed in the presence of sodium dodecyl sulfate (SDS) in a thin-layer gel supported by a glass plate, treated with the nonionic detergent Triton X-100, and specifically stained for the sugar-releasing activity of these enzymes. Staining is based on conversion of monosugars or a sugar phosphate to glucose-6-phosphate by the appropriate intermediary enzymes, reduction of NADP+ to NADPH, and accumulation of reduced Nitroblue Tetrazolium in the gel. Among the enzymes tested, alpha-glucosidase, beta-glucosidase and beta-mannosidase could not be renatured, whereas beta-fructofuranosidase and alpha-mannosidase could be renatured unless heated before electrophoresis. Sucrose phosphorylase, glucosyltransferase and fructosyltransferase, which are single-peptide proteins with no cystine bond, could be renatured even after pretreatment with SDS and/or mercaptoethanol at 100 degrees C for 10 min. However, exclusive heating remarkably decreased the activities of these enzymes. Two-dimensional separation of the five renaturable enzymes was done in a single thin-layer gel, using SDS-electrophoresis in the first dimension and isoelectric focusing in the second dimension.
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PMID:Renaturation and activity staining of glycosidases and glycosyltransferases in gels after sodium dodecyl sulfate-electrophoresis. 752 70

New panosialin analog, panosialins D and wD have been isolated from the culture broth of Streptomyces sp. OH-5186. Their structures were elucidated as 5-(13-methylpentadecyl)-1,3-benzenediol bis(sodium sulfate) and 5-(13-methylpentadecyl)-1,3-benzenediol 1-(sodium sulfate), respectively. They showed strong inhibitory activity against alpha-mannosidase, alpha-glucosidase, and beta-glucosidase. Panosialins wA-wD mixture also showed weak mitogenic activity but suppressed the mitogen induced activity.
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PMID:New glycosidases inhibitors, panosialins D and wD produced by Streptomyces sp. OH-5186. 773 Jan 53

alpha-Glucosidase was partially purified 103-fold from a cell-free extract of Torulaspora pretoriensis YK-1 by column chromatography on Toyopearl HW55F, DEAE-Toyopearl 650M, hydroxylapatite and phenyl-Toyopearl 650M. Further purification by preparative polyacrylamide gel electrophoresis (PAGE) gave the homogenous protein, but the specific activity was reduced. The molecular weight of the enzyme was estimated to be 69,000 by SDS-PAGE and 60,000 by gel filtration. Optimum pH and temperature were 6.8 and 35 degrees C, respectively. The enzyme was inhibited strongly by AgNO3, HgCl2, sodium dodecyl sulfate, and N-ethylmaleimide. The Km (mM) for p-nitrophenyl alpha-D-glucopyranoside, maltose, maltotriose, isomaltose, methyl alpha-glucoside, and sucrose were 0.15, 150, 45, 17, 18, and 29, and Vmax (mumol/min/mg protein) for those substrates were 87, 0.23, 2.4, 9.0, 12, and 7.4, respectively. The N-terminal amino acid sequence of the enzyme was PEVKNHPETQPKWWKEATVY. The properties of alpha-glucosidase from T. pretoriensis YK-1 were similar to those from Saccharomyces cerevisiae.
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PMID:Purification and characterization of alpha-glucosidase from Torulaspora pretoriensis YK-1. 776 39

We examined the effect of the growth factors, human epidermal growth factor (hEGF) and insulin, on corneal metabolism during storage in Optisol, a chondroitin-sulfate-(CS)-based storage medium. Paired cat corneas, in either Optisol only or Optisol with growth factor(s), were analyzed using ex vivo 31P nuclear magnetic resonance, after storage for 1 week at 4 degrees C. Lysosomal enzyme release into the media at the end of the storage period also was measured fluorometrically. Both epithelial-intact and epithelial-denuded corneal pairs were examined for all conditions. Considering corneas having either intact epithelia or epithelium-denuded corneas, the addition of either growth factor alone to Optisol did not alter the relative corneal concentrations of five of the six phosphatic metabolite spectral bands measured or two metabolic ratios calculated from these bands. Phosphodiesters, however, were significantly lower in corneas stored in Optisol containing both hEGF and insulin (23%) than in corneas stored in Optisol alone (30%). Intracorneal pH was unaffected by the addition of growth factor(s). A significantly higher release of alpha-glucosidase and alpha-mannosidase was noted in those corneas stored in Optisol containing both hEGF and insulin. Optisol maintains high-energy phosphate corneal metabolism similar to other CS-based media, K-Sol and Chondroitin Sulfate Corneal Storage Medium (CSM). The addition of the growth factors hEGF and insulin to Optisol alters corneal metabolic activity during storage in a manner indicative of conserving corneal phospholipids.
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PMID:The effect of hEGF and insulin on corneal metabolism during Optisol storage. 803 75


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