Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.21 (beta-glucosidase)
3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effect of ethanol on functional activity of isolated perfused rat liver was studied (rate of O2 utilization, absorption of bromosulpholeine from perfusate, bile formation); total activity and activity in supernatant of nine marker enzymes were also determined (malate dehydrogenase, beta-glucuronidase, arylsulphatases A and B, beta-galactosidase, beta-glucosidase, acetylesterase, glucoso-6-phosphatase, alanine aminotransferase and aspartate aminotransferase). Activity of the enzymes was simultaneously studied in perfusate. Ethanol (0.5%) caused distinct impairement in functional activity of isolated liver; rate of bile formation and absorption of bromosulpholeine from perfusate were primarily altered. Degree of impairements in functional activity of liver tissue correlated with the concentration of ethanol in perfusate. In analysis of correlation between the total activity of the enzymes in liver tissue and their activity in supernatants and perfusate it was shown that the concentration (1%) of ethanol used did not produce damaye effect on plasma membranes and membranes of subcellular structures of hepatocytes, but, within certain limits, it displayed a stabilizing effect.
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PMID:[Effect of ethanol on stability of cell membranes in experiments using isolated liver]. 121 Jan 8

Ethanol feeding to rats for 40 days enhanced (p < 0.001) the activities of alkaline phosphatase, sucrase, gamma-glutamyltransferase (GTP), and p-nitrophenyl (PNP)-beta-D-galactosidase (p < 0.05) with no change in leucine amino peptidase (LAP) and PNP-beta-D-glucosidase activities in intestine compared with control rats. The activities of alkaline phosphatase, sucrase, and GTP were diminished (p < 0.01) in ethanol-fed malnourished rats. There was no change in LAP activity, but the levels of glucosidase and galactosidase were elevated under these conditions. Brush-border sialic acid, fucose, hexose, and hexosamine contents were elevated in ethanol-fed protein-deficient animals. Ethanol administration to normally fed rats elevated the membrane sialic acid and hexose contents, reduced fucose content, and had no effect on brush-border hexosamine content compared with the control group. These results are in agreement with data on lectin binding to brush borders under these conditions. Alcohol ingestion reduced the incorporation of [14C]-glucosamine into brush borders in rats maintained on an 18% protein diet but augmented the incorporation of [14C]-glucosamine and [14C]-mannose in protein-malnourished membranes. These observations suggest that nutrition status influences the sensitivity of microvillus membrane glycosylation to ethanol feeding in rat intestine.
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PMID:Chronic ethanol feeding and microvillus membrane glycosylation in normal and protein-malnourished rat intestine. 142 85

The beta-glucosidase encoded by the bglA gene from Bacillus polymyxa was overproduced in Escherichia coli by using a plasmid in which bglA is under control of the lacI promoter. Induction with isopropyl-beta-D-thiogalactopyranoside allowed an increase in the specific activity of the enzyme of about 100 times the basal level of gene expression. The enzyme was purified by a two-step procedure involving salting out with ammonium sulfate and ion-exchange chromatography with DEAE-cellulose. Fractions of beta-glucosidase activity recovered by this procedure, after electrophoresis in an acrylamide gel and staining with silver nitrate, yielded a single band of protein. This band was shown by a zymogram to correspond to beta-glucosidase activity. The purified protein showed an apparent molecular mass of 50 kDa and an isoelectric point of 4.6, values in agreement with those expected from the nucleotide sequence of the gene. Km values of the enzyme, with either cellobiose or p-nitrophenyl-beta-D-glucoside as the substrate, were determined. It was shown that the enzyme is competitively inhibited by glucose. The effects of different metallic ions and other agents were studied. Hg2+ was strongly inhibitory, while none of the other cations tested had any significant effect. Ethanol did not show the stimulating effect observed with other beta-glucosidases. The mechanism of enzyme action was investigated. High-pressure liquid chromatography analysis with cellobiose as the substrate confirmed previous data revealing the formation of two products, glucose and another, unidentified, compound. Results presented here indicate that this compound is cellotriose formed by transglycosylation.
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PMID:Purification and characterization of a Bacillus polymyxa beta-glucosidase expressed in Escherichia coli. 156 36

Ethanol inhibition of several hydrolases (sucrase, maltase, trehalase, melezitase and cellobiase) has been measured in both highly ethanol-tolerant Saccharomyces strains (R) and in Candida strains less tolerant to ethanol (S). Cells were either grown in the presence of ethanol and the activities of the enzymes measured without preincubation in this alcohol ("in situ" inhibition assay), or the culture was grown in the absence of ethanol and the activities of the enzymes were determined after preincubation and in the presence of this compound ("in vitro" inhibition assay). Ethanol inhibition (Ki values) of sucrase, maltase, trehalase, and melezitase was quite different for these different enzymes in the same strain (R or S), but similar for the same enzyme in different strains (R and S). The Ki values for cellobiase, which is absent from the R strain, were higher when induced than at the basal level and higher in in vitro assays than in in situ assays. This suggests that the inhibition observed in situ is mainly the result of an inhibition of other proteins related to cellobiase (i.e., those involved in its synthesis) but not a direct inactivation of the enzyme by ethanol. Accordingly, when hybrids between Saccharomyces (R) and Candida (S) strains were constructed by protoplast fusion, and cellobiase was measured in the parental Candida strain and some of the hybrids, there was an increase in the Ki values in the in situ assays from 2.25% ethanol in Candida to 5.5% in some of the hybrids.
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PMID:Ethanol inhibition of Saccharomyces and Candida enzymes. 266 87

The kinetic parameters of almond beta-glucosidase (beta-D-glucoside glucohydrolase; EC 3.2.1.21), using pNGP as substrate were kM = 2.24 +/- 0.11 mM and Vmax 588 +/- 25.1 U/mg protein. Only Hg(II) and Cu(II) showed irreversible inactivation of the enzyme. However, when these metals were present in the reaction system the inhibition effects were consistent with a mixed-type inhibition pattern (Cu(II) ki: 5.08 mM and Hg(II) ki: 0.07 mM). The glucose kinetic effect was also consistent with a mixed-type inhibition (ki = 406 mM) pattern with pNGP as varied substrate. Ethanol displayed the kinetic pattern of competitive inhibition (ki = 640 mM).
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PMID:Effects of glucose, ethanol, Hg(II) and Cu(II) on almond beta-glucosidase. 798 62

Candida peltata (NRRL Y-6888) produced beta-glucosidase when grown in liquid culture on various substrates (glucose, xylose, L-arabinose, cellobiose, sucrose, and maltose). An extracellular beta-glucosidase was purified 1,800-fold to homogeneity from the culture supernatant of the yeast grown on glucose by salting out with ammonium sulfate, ion-exchange chromatography with DEAE Bio-Gel A agarose, Bio-Gel A-0.5m gel filtration, and cellobiose-Sepharose affinity chromatography. The enzyme was a monomeric protein with an apparent molecular weight of 43,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration. It was optimally active at pH 5.0 and 50 degrees C and had a specific activity of 108 mumol.min-1.mg of protein-1 against p-nitrophenyl-beta-D-glucoside (pNP beta G). The purified beta-glucosidase readily hydrolyzed pNP beta G, cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose, with Km values of 2.3, 66, 39, 35, 21, and 18 mM, respectively. The enzyme was highly tolerant to glucose inhibition, with a Ki of 1.4 M (252 mg/ml). Substrate inhibition was not observed with 40 mM pNP beta G or 15% cellobiose. The enzyme did not require divalent cations for activity, and its activity was not affected by p-chloromercuribenzoate (0.2 mM), EDTA (10 mM), or dithiothreitol (10 mM). Ethanol at an optimal concentration (0.75%, vol/vol) stimulated the initial enzyme activity by only 11%. Cellobiose (10%, wt/vol) was almost completely hydrolyzed to glucose by the purified beta-glucosidase (1.5 U/ml) in both the absence and presence of glucose (6%). Glucose production was enhanced by 8.3% when microcrystalline cellulose (2%, wt/vol) was treated for 24 h with a commercial cellulase preparation (cellulase, 5 U/ml; beta-glucosidase, 0.45 U/ml) that was supplemented with purified beta-glucosidase (0.4 U/ml).
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PMID:Production, purification, and characterization of a highly glucose-tolerant novel beta-glucosidase from Candida peltata. 879 5

Ethanol production was studied in simultaneous saccharification and fermentation (SSF) of steam-pretreated spruce at 42 degrees C, using a thermotolerant yeast. Three yeast strains of Kluyveromyces marxianus were compared in test fermentations. SSF experiments were performed with the best of these on 5% (w/w) of substrate, at a cellulase loading of 37 filter paper units/g of cellulose, and a beta-glucosidase loading of 38 IU/g of cellulose. The detoxification of the substrate and the lack of pH control in the experiments increased the final ethanol concentration. The final ethanol yield was 15% lower compared to SSF with Saccharomyces cerevisiae at 37 degrees C, owing to the cessation of ethanol fermentation after the first 10 h.
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PMID:Simultaneous saccharification and fermentation of steam-pretreated spruce to ethanol. 1084 80

A color variant strain of Aureobasidium pullulans (NRRL Y-12974) produced beta-glucosidase activity when grown in liquid culture on a variety of carbon sources, such as cellobiose, xylose, arabinose, lactose, sucrose, maltose, glucose, xylitol, xylan, cellulose, starch, and pullulan. An extracellular beta-glucosidase was purified 129-fold to homogeneity from the cell-free culture broth of the organism grown on corn bran. The purification protocol included ammonium sulfate treatment, CM Bio-Gel A agarose column chromatography, and gel filtrations on Bio-Gel A-0.5m and Sephacryl S-200. The beta-glucosidase was a glycoprotein with native molecular weight of 340,000 and was composed of two subunits with molecular weights of about 165,000. The enzyme displayed optimal activity at 75 degrees C and pH 4.5 and had a specific activity of 315 mumol . min . mg of protein under these conditions. The purified beta-glucosidase was active against p-nitrophenyl-beta-d-glucoside, cellobiose, cellotriose, cellotetraose, cellopentaose, cellohexaose, and celloheptaose, with K(m) values of 1.17, 1.00, 0.34, 0.36, 0.64, 0.68, and 1.65 mM, respectively. The enzyme activity was competitively inhibited by glucose (K(i) = 5.65 mM), while fructose, arabinose, galactose, mannose, and xylose (each at 56 mM) and sucrose and lactose (each at 29 mM) were not inhibitory. The enzyme did not require a metal ion for activity, and its activity was not affected by p-chloromercuribenzoate (0.2 mM), EDTA (10 mM), or dithiothreitol (10 mM). Ethanol (7.5%, vol/vol) stimulated the initial enzyme activity by 15%. Glucose production was enhanced by 7.9% when microcrystalline cellulose (2%, wt/vol) was treated for 48 h with a commercial cellulase preparation (5 U/ml) that was supplemented with the purified beta-glucosidase (0.21 U/ml) from A. pullulans.
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PMID:Production, Purification, and Properties of a Thermostable beta-Glucosidase from a Color Variant Strain of Aureobasidium pullulans. 1634 15

Total glycolipid content of Saccharomyces cerevisiae cells increased in ethanol-treated yeast cells. Sialic acid and hexosamine contents of glycolipids from ethanol-treated cells decreased, whereas those of hexoses increased. Increased sialidase activity in the presence of ethanol may be responsible for the decrease in sialic acid content of glycolipids. The saccharide moieties of glycolipids of S. cerevisiae consisted of fucose, mannose, galactose, and glucose. Ethanol treatment of yeast cells caused an increase in glucose and a decrease in galactose content of glycolipids. The changes in glucose content can be related to changes in beta-glucosidase activity under alcohol stress. The content of cerebrosides, sulfatides, and monoglucosyldiglycerides was enhanced following ethanol treatment. An increase in cerebroside as well as in sulfatide content during alcohol stress might play an important role in stabilizing the membrane both physically and structurally. Such variations in glycolipid content and composition of S. cerevisiae cells may represent an adaptive response to ethanol stress.
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PMID:Ethanol-induced changes in glycolipids of Saccharomyces cerevisiae. 1663 81

Purified beta-glucosidase fromCellulomonas biazotea had an apparentK (m) andV for 2-nitrophenyl beta-D: -glucopyranoside (oNPG) of 0.416 mmol/L and 0.22 U/mg protein, respectively. The activation energy for the hydrolysis of pNPG of beta-glucosidase was 65 kJ/mol. The inhibition by Mn(2+) vs. oNPG of parental beta-glucosidase was of mixed type with apparent inhibition constants of 0.19 and 0.60 micromol/L for the enzyme and enzyme-substrate complex, respectively. Ethanol at lower concentrations activated while at higher concentrations it inhibited the enzyme. The determination of apparent pK (a)'s at different temperatures and in the presence of 30 % dioxane indicated two carboxyl groups which control theV value. The thermal stability of beta-glucosidase decreased in the presence of 10 % ethanol. The half-life of beta-glucosidase in 1.75 mol/L urea at 35 degrees C was 145 min, as determined by 0-9 mol/L transverse urea gradient-PAGE.
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PMID:Kinetic analysis of the active site of an intracellular beta-glucosidase fromCellulomonas biazotea. 1845 27


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