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:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

Leukocytes were obtained from 14 healthy subjects, one patient with the infantile form, two patients with the adult variant of acid maltase deficiency, two patients with chronic myelocytic leukemia, two patients with acute myeloid leukemia, and two patients with chronic lymphotic leukemia. In addition, lymphocytes were prepared from three normal subjects, and five established lymphoid lines were used. Cells were extracted either with Triton 0, 2%, or with water followed by 0.2% Triton. alpha-Glucosidase activity was measured in water homogenates, water extracts after centrifugation, and Triton extracts, with or without antisera directed against acid maltase (EC 3.2.1.3) and renal maltase (EC 3.2.1.20). The percentage of acid and renal maltases was then calculated in each soluble fraction. Normal whole leukocytes (mostly granulocytes) contain both acid and "renal" maltases, whereas normal lymphocytes contain very little or no "renal maltase." This isozyme is present in chronic myelocytic leukemia, but is absent in acute myeloid and chronic lymphocytic leukemia as well as in established lymphoid lines. Acid maltase is almost completely extracted with water, whereas renal maltase is extracted only with Triton. From the results, it appears that for the diagnosis of alpha glucosidase deficiency, cells should be extracted in water and centrifuged before determination. Lymphocytes, which are devoid of renal maltase, are a better diagnostic material than are granulocytes.
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PMID:White blood cells and the diagnosis of alpha-glucosidase deficiency. 676 91

The present study examines the role of cardiac lysosomal enzymes in the pathogenesis of the cardiomyopathy that develops in genetically diabetic C57BL/KsJ db+/db+ mice. Db+/db+ mice and littermate controls were sacrificed as age-matched pairs between 5-26 weeks of age. C57BL/6J ob/ob mice and littermates served as other controls. The hearts were excised, homogenized, and the following enzymatic activities measured: N-Acetyl-beta-glucosaminidase, N-acetyl-beta-galactosaminidase, beta-glucosaminidase, aryl sulphatase, alpha-mannosidase, alpha-glucosidase, beta-galactosidase, beta glucosidase, total p-nitrophenyl phosphatase, acid phosphatase and 5'-phosphodiesterase type IV. There is a progressive decrease in cardiac lysosomal enzyme activities of db+/db+ mice for the period 5-21 weeks of age. All enzyme activity is depressed significantly during the 9-21 week interval with beta-glucuronidase, aryl sulphatase and beta-glucosidase decreased about 40-50%. The decrease in lysosomal enzyme activity can explain the accumulation of large residual bodies and interstitial material in the myocardium of the db+/db+ animals
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PMID:Lysosomal enzymes in experimental diabetic cardiomyopathy. 678 Feb 37

The activities of seven lysosomal enzymes (alpha-D-glucosidase, beta-D-galactosidase, beta-D-glucuronidase, hexosaminidase, alpha-L-fucosidase, alpha-D-mannosidase, acid phosphatases) were studied in the serum of 31 untreated patients with Graves' disease, 30 treated hyperthyroid patients whose clinical abnormalities had disappeared and whose hormones had returned to euthyroid levels, and 34 controls. The hyperthyroid state is characterized by increased serum levels of alpha-D-glucosidase, beta-D-glucuronidase, hexosaminidase and especially of alpha-L-glucosidase and alpha-D-mannosidase. In contrast, neither beta-D-galactosidase nor acid phosphatases serum levels were significantly modified. After antithyroid treatment, the activities of these enzymes returned to normal levels, except for alpha-D-mannosidase. The interpretation of these changes in serum acid hydrolases activities is controversial.
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PMID:Serum lysosomal acid hydrolase activities in Graves' disease. 680 24

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

We have previously defined two isozymes of neutral alpha-glucosidase (alpha-D-glucoside glucohydrolase, EC 3.2.1.20) on the basis of differences in electrophoretic mobility and designated these neutral alpha-glucosidase AB and alpha-glucosidase C (Swallow, D.M., Corney, G., Harris, H. and Hirschhorn, R. (1975) Ann. Hum. Gen. 38, 391-406). We now describe differences between the two isozymes with respect to molecular weight, solubility in (NH4)2SO4, glycosylation, isoelectric point and substrate specificities. Neutral alpha-glucosidase C is precipitable in 40-60% (NH4)2SO4, has a molecular weight of 92 000, an isoelectric point of 5.5 and releases glucose from glycogen as well as from low molecular weight artificial and natural substrates containing alpha 1-4 glucosidic linkages. Neutral alpha-glucosidase AB precipitates at 0-40% (NH4)2SO4, binds to concanavalin A, has a molecular weight of greater than 150 000, and does not utilize alpha 1-4 linked glucose substrates larger than a disaccharide. Neutral alpha-glucosidase AB migrates more rapidly to the anode than alpha-glucosidase C when agarose, Cellogel, acrylamide or starch are used as support media. Both isozymes are equally inhibited by Zn2+.
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PMID:Characterization of neutral isozymes of human alpha-glucosidase: differences in substrate specificity, molecular weight and electrophoretic mobility. 701 80

In a two-factorial balance trial two dietary protein levels of 12 and 15% the effect of a supplement of 50 mg alpha-glucosidase inhibitor (Bay g 5421) per kilogram food on nutrient digestibility, protein, and energy balance was tested in growing rats. At both protein levels the alpha-glucosidase inhibitor reduced the apparent digestibility of protein by maximal 8 and 4%, those of starch and energy only by 3 and 1%, respectively. With the low protein supply the protein and energy retention was decreased each by 13% when the inhibitor was given. On the basis of metabolizable energy, 6 and 19% less energy in form of protein and fat, respectively, have been deposited compared with the control group. These results may indicate also an effect of the glucosidase inhibitor on the intermediary metabolism.
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PMID:[Effect of inhibition of intestinal glucosidase on protein and energy balance in rats]. 702 47

Certain effects of insulin administration on newborn rat hepatocytes were studied using biochemical assays, electron microscopy and quantitative morphometry. Insulin produced an inhibition of postnatal hyaloplasmic glycogen breakdown, of lysosomal glycogen breakdown and of the development of the Golgi apparatus. The insulin-treated animals showed a low activity of the enzyme, acid alpha 1,4-glucosidase (maltase). The results support the postulate that the catabolism of lysosomal glycogen is controlled by those agents that regulate the catabolism of hyaloplasmic glycogen (Am. J. Path., 63: 1-17 and Am. J. Path., 63: 23-36, 1971). Control could be mediated through changes in the activity of the lysosomal acid alpha 1,4-glucosidase.
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PMID:An electron microscopic and biochemical study of the effects of insulin on newborn rat hepatocytes. 703 26

The synthesis of 3-nitro-4-(6-aminohexylamido)phenylboronic acid is described. The properties of two novel forms of immobilized phenylboronate agarose adsorbents [m-aminophenylboronic acid-Matrex Gel and 3-nitro-4-(6-aminohexylamido)phenylboronic acid-Sepharose CL-6B] were investigated. Both gels bind and selectively retard the glycoprotein alpha-glucosidase from yeast. The retardation is affected by following parameters: (i) pH, (ii) presence of sugar, (iii) concentration of sugar and (iv) buffer species (especially triethanolamine). Five sugars were studied, namely sorbitol, fructose, ribose, glucose and maltose. The concentration of sugar required to produce significant retardation increased in the above order, whereas the ability of sugar to form a complex with boron decreases in the same order. These effects were observed with crude as well as pure enzyme. Since alpha-glucosidase is a glycoprotein, it is proposed that this protein is mainly bound to these immobilized phenylboronates via sugar (glyco) residues. Displacement of the enzyme from the column is effected by the sugar in the buffer (or in a preincubation mixture). However, the marked pH-dependence (this retardation effect could only be observed at pH 7.4) suggests that these results are not due solely to hydrophobic or ionic mechanisms and are more complex than simple sugar-phenylboronic acid interactions.
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PMID:Affinity chromatography of yeast alpha-glucosidase using ligand-mediated chromatography on immobilized phenylboronic acids. 703 22

The in situ kinetic constants of neutral alpha- glucosidase were determined in the atrophic jejunal mucosa of self-emptying blind loops and in corresponding jejunal segments of control rats, using a quantitative histochemical technique. The apparent maximum velosity (Vmax) and km values were calculated from absorbance measurements of an azo dye-deposit formed in the brush border membrane at the villus base and at the transition zone between the middle and upper one-third of the villus. In the controls a significant increase of apparent Vmax and substrate affinity (decrease of apparent Km) was obtained, corresponding to enterocyte maturation along the villi. The mucosal atrophy in self-emptying blind loops was accompanied by a significant decrease of apparent Vmax of neutral alpha-glucosidase at both representative villus sites, but the substrate affinity was increased at both sites. The results indicate that alpha-glucosidase activity was reduced when measured at the cellular level of two representative villus sites in the atrophic jejunal mucosa, possibly due to the absence of substrate-effected enzyme induction. The decrease on hydrolytic enzyme activity was not matched by a compensatory increase in substrate affinity.
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PMID:Kinetic properties of neutral alpha-glucosidase in the atrophic mucosa of self-emptying blind loops of rat jejunum: a microdensitometric study at two different villus sites. 704 85


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