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)

Maltase activity (EC 3.2.1.20) was solubilized from rabbit kidney brush-border membrane by using 1.0% Triton X-100 and purified 230-fold with an overall recovery of 30%. The purification procedure makes use of heat precipitation, chromatography on DE-52 DEAE-cellulose and gel filtration on Sephacryl S-300. Rabbit kidney brush border exhibited glucoamylase activity with a maltase/glucoamylase ratio of 1.5:1 to 2.0:1. During purification the maltase and glucoamylase activities behaved identically. The Mr of the complex is 590,000, and it appears to be composed of eight identical subunits linked by disulphide bridges.
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PMID:Neutral maltase/glucoamylase from rabbit renal cortex. 250 56

A procedure for the purification of neutral maltase from human polymorphonuclear leukocytes is described, involving solubilization with Triton X-100, proteolytic attack and three chromatographic steps: DEAE ion exchange, AcA 22 gel filtration and a second DEAE chromatography. The enzyme was obtained with a final specific activity of 30 units/mg of protein, comparable with that of other neutral maltases previously purified. The Mr of the enzyme was 550,000 as determined by gel filtration. SDS/polyacrylamide-gel electrophoresis, under non-denaturing conditions, led to a major band of 500,000 and a minor one of 260,000, both active, suggesting a polymeric or aggregated form of the protein. The catalytic properties of the human granulocytic neutral maltase were investigated. The pH optimum was around 6. The enzyme exhibited a broad range of substrate specificity, hydrolysing di- and oligosaccharides with alpha (1----2), alpha (1----3) and alpha (1----4) glucosidic linkages. The highest activities were observed for alpha (1----4) glucose oligomers of three to five residues. It was also found to hydrolyse polysaccharides such as starch and glycogen. The results of the inhibition studies are interpreted in terms of the existence of a large site including several subsites. The enzyme properties are broadly similar to those observed for other purified neutral alpha-glucosidases, in particular that of human kidney origin.
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PMID:Purification and properties of neutral maltase from human granulocytes. 268 33

The activities of lysosomal maltase in the serum, bile and liver were determined in intrahepatic cholestasis rats induced by alpha-naphtylisothiocyanate (ANIT, 200 mg/kg, i.p.), and compared with changes in alkaline phosphatase (ALP) activity. Moreover, the influences of endogenous bile acids on the release of maltase activity from the liver in intrahepatic cholestasis rats were studied. The maltase activities in the serum and bile significantly increased from 4 and 8 h after the intraperitoneal administration of ANIT, respectively. Conversely, a significant decrease in liver maltase activity was observed from 4 h after the injection of ANIT. On the other hand, total bile acid concentrations in the serum and bile significantly increased immediately after the treatment of ANIT, when biliary bile acid, exogenous bile acid or Triton X-100 was added to lysosomal fraction in the liver, the maltase activity in the supernate after the reaction significantly increased in proportion to the concentration of each substance added to the liver lysosome. These results suggested that maltase might be released from liver lysosomal membrane by surface active-action of bile acid accumulated in the liver after the administration of ANIT. Moreover, the changes in ALP activities in the serum, bile and liver after the administration of ANIT were almost similar to those in maltase activity.
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PMID:[The influences of endogenous bile acids on maltase and alkaline phosphatase activities in intrahepatic cholestasis rats]. 269 43

Various lysosomal acid hydrolases from tissues of Niemann-Pick mice, a mutant strain of C57BL/KsJ mice (spm/spm), were examined and compared to those from control mice. Activities of beta-hexosaminidase, beta-galactosidase, acid phosphatase, and cathepsin L were elevated in the liver and spleen of the affected mice, whereas no significant changes in beta-glucosidase and acid alpha-glucosidase were observed. Alpha-Mannosidase and neutral alpha-glucosidase activities were rather decreased in the affected mouse liver. The level of beta-hexosaminidase in the Niemann-Pick mice was raised sixfold in the liver and two- to threefold in the spleen and brain, whereas its total activity was decreased in the kidney. Sixty to ninety percent of total activity of lysosomal hydrolases was solubilized with 0.1% Triton X-100 in control mice, but most of the beta-hexosaminidase activity of the Niemann-Pick mice remained associated with the membrane fraction of liver lysosomes. The beta-hexosaminidase of the Niemann-Pick mice was appreciably stable when heated at 55 degrees C, while hydrolases of the affected mice and all of the enzymes tested in control mice were heat labile. The relative content of two beta-hexosaminidase fractions separated by DEAE-cellulose column chromatography was 8% for beta-hexosaminidase I and 92% for beta-hexosaminidase II in the case of the control mouse liver. The isozyme pattern of hexosaminidases in Niemann-Pick mice was similar to that of control enzymes. However, the beta-hexosaminidase II accumulated in Niemann-Pick mouse liver was different from that of the control in optimum pH, Km values and thermostability.
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PMID:Properties of lysosomal beta-hexosaminidase accumulated in Niemann-Pick mouse liver. 294 29

Cultured skin fibroblasts derived from patients with cystic fibrosis contain 2.1-fold more acid alpha-glucosidase (EC 3.2.1.3) than normal fibroblasts. This difference is amplified to 2.3-fold when the cells are extracted in Triton X-100. In a study of 14 fibroblast cell lines derived from CF homozygotes and heterozygotes, normal individuals and patients with other recessively inherited disorders, normal individuals could be distinguished from either CF homozygotes or heterozygotes based on the ratio of acid alpha-glucosidase to beta-hexosaminidase when fibroblasts were extracted in either water or Triton X-100. However, the best distinction could be made with water extracts as there was no overlap among individual data points in the three categories. The acid to neural alpha-glucosidase ratio only distinguished CF homozygotes from normal individuals when cells were extracted in Triton X-100. The use of a ratio relationship of acid alpha-glucosidase with beta-hexosaminidase allows the comparison of data from multiple experiments on different days of assay and on cells at different passage numbers. These results suggest that alpha glucosidase may have a role in the primary defect in cystic fibrosis.
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PMID:Alterations in specific activity of lysosomal alpha-glucosidase in cystic fibrosis. 307 37

Rat intestinal microvillus maltase-glucoamylase was isolated by detergent extraction and purification in the presence of protease inhibitors as previously described and incorporated into phospholipid vesicles. After purification of the vesicles on Sephadex G-50, maltase was labelled with 3-trifluoromethyl-3-(m-[125I]iodophenyl) diazirine ([125I]TID) by photolysis using a water-jacketed mercury vapour lamp with a saturated CuSO4 filter. The labelled enzyme was extracted with acetone, resuspended in 1% Triton X-100, reincorporated into phospholipid vesicles, and digested with activated papain to release the hydrophilic polar head of the enzyme from the vesicle bilayer. Vesicle-bound and free enzyme components were separated on Sepharose 4B. Ninety percent of the enzymatic activity was free, while a similar percentage of radioactive label remained with the vesicles in keeping with the separation of an active polar headpiece from a labelled apolar peptide in the lipid bilayer. The vesicle fractions were subjected to chromatography on Sephadex LH-60 with ethanol--formic acid (7:3) as the eluant. A single radioactive peak (14 kilodaltons (kDa)) was separated from labelled lipid. Sodium dodecyl sulfate--polyacrylamide gel electrophoresis of the peak showed a radioactive doublet of 26-28 kDa, possibly representing a dimer. No other labelled peptides were found. These results suggest that detergent-solubilized maltase-glucoamylase is inserted into the phospholipid bilayer via an apolar peptide with a minimum molecular mass of 14 kDa. The peptide probably represents a terminal anchor segment of the 145-kDa subunit which is converted to 130 kDa when the membrane-bound enzyme is solubilized by papain.
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PMID:Hydrophobic binding domains of rat intestinal maltase-glucoamylase. 309 59

Homogenates of Giardia lamblia trophozoites exhibited the following hydrolase activities: acid phosphatase (EC 3.1.3.2), proteinase (EC 3.1.4) with urea-denatured hemoglobin and N-benzoyl-DL-arginine-2-naphthylamide as substrates, deoxyribonuclease (EC 3.1.4.5), and ribonuclease (EC 2.7.7.16). beta-N-Acetylglucosaminidase (EC 3.2.1.30), beta-galactosidase (EC 3.2.1.23), beta-glucuronidase (EC 3.2.1.31), alpha-D-glucosidase (EC 3.2.1.20), beta-D-glucosidase (EC 3.2.1.21), and beta-D-xylosidase (EC 3.2.1.37) activities were below the level of detection. Differential and isopycnic centrifugation of homogenates demonstrated that giardial hydrolases were localized in a single-particle population sedimenting at 7200g for 30 min. The particles had a buoyant density in sucrose of 1.15 and exhibited latency. Latency was completely destroyed by Triton X-100 or 15 cycles of freezing and thawing. After centrifugation of Triton- or freeze-thaw-treated particle fractions, the hydrolase activities, though no longer latent, were still sedimentable suggesting tight binding to the organelle membrane. Latency was destroyed simultaneously for all hydrolases, in direct proportion to the amount of Triton added to a particle preparation or to the number of times a particle preparation was subjected to freezing and thawing. These results support the suggestion that the hydrolases of G. lamblia trophozoites are localized in a single-particle population of lysosome-like organelles.
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PMID:Giardia lamblia: localization of hydrolase activities in lysosome-like organelles of trophozoites. 327 50

Highly purified microvillus membrane vesicles isolated from rat small intestine were enriched in sucrase, maltase, and aminopeptidase activities. Approximately 90-95% of each enzyme was released from the membrane fraction by treatment with detergent (Triton X-100) and sonication. Using untreated and solubilized preparations, the effect of lectin binding on the activity of each of the three enzymes was measured. It was observed that wheat germ agglutinin (WGA) and phytohemagglutinin (PHA) dramatically enhanced the activity of membrane-bound maltase but had much less effect on the detergent solubilized enzyme. Under the same conditions aminopeptidase activity was inhibited by WGA and PHA while sucrase activity was not affected. These alterations in enzyme activity occurred at lectin concentrations that also precipitated each solubilized enzyme from solution. Inhibitory sugars prevented the alterations in enzyme activity suggesting that the effect is due to the binding of lectin to specific carbohydrate structures. Enhancement of membrane-bound maltase activity by WGA and PHA was shown to be temperature dependent indicating that the lipid environment of the microvillus membrane may play a role in mediating the lectin effect. A kinetic analysis of the changes in maltase activity induced by these two lectins was due solely to an increase in Vmax. Two other lectins used in this study (concanavalin A and Ricinus communis agglutinin) did not readily precipitate the enzymes in question or alter their activity. These results show that binding of lectins to brush border membranes can induce variable changes in the activity of several membrane associated hydrolases, and suggest that similar changes may occur in vivo in the presence of dietary lectin.
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PMID:Effect of lectins on the activity of brush border membrane-bound enzymes of rat small intestine. 390 78

Several approaches were adopted for the disruption and removal of the tegumental surface from protoscoleces of the horse strain of the hydatid organism, Echinococcus granulosus. The effectiveness of each method and the purity of subsequent microthrix-enriched fractions obtained by differential centrifugation were evaluated by electron microscopy, by the amount of protein released and by the degree of enrichment of surface plasma membrane marker enzymes. Incubation in saponin for 10 min produced the purest microtriche preparation, but in low yield; freeze/thawing, incubation in Triton X-100 for 10 min or in saponin for 20 min produced fractions containing significant amounts of relatively pure microtriches, but mild homogenization was a poor method for surface disruption and subsequent isolation of microtriches. Phosphodiesterase, adenosine triphosphatase (total and ouabain-inhibited), leucine aminopeptidase and glutamyltransferase were active in the protoscoleces but none were enriched in any of the microthrix fractions. In contrast, alkaline phosphatase, acid phosphatase, 5' nucleotidase and maltase were enriched significantly in all of the isolated microtriche preparations, which suggests that these enzymes are predominantly surface membrane bound. The protein profiles of the microthrix-enriched fractions, following SDS-PAGE, were basically similar, although there were some qualitative and quantitative differences in the proteins released by each isolation procedure. Three major PAS-staining components were present in all the preparations and these probably originated from the glycocalyx. One of these PAS-positive components, with an approximate molecular weight of 110 kDa, may be a glycoprotein specific to the horse strain of E. granulosus.
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PMID:Isolation, fractionation and partial characterization of the tegumental surface from protoscoleces of the hydatid organism, Echinococcus granulosus. 398 50

The ability of eight stripping agents to solubilize five marker enzymes from rat renal brush border membranes isolated by three different preparative methods was examined. Protein and enzyme activities - alkaline phosphatase (APase), L-leucine aminopeptidase (LAPase), gamma-glutamyl transpeptidase (GGTase), gamma-glutamyl hydrolase (GGHase) and maltase - solubilized by the treatments were expressed as percent of total activity recovered in excess of control values. The relative enzyme activity and the solubilization factor were determined for each marker enzyme in every treated sample and the treatments with the eight agents compared. Trypsin treatment released > 80% of LAPase and < 10% of total membrane protein. Papain treatment released only 16--23% of total membrane protein but most of the enzyme activities except APase. Neuraminidase had no solubilizing effect. 4--10% of total membrane protein was solubilized by LiCl treatment but no marker enzyme activities were released. Less total membrane protein was released by treatment with proteolytic enzymes or LiCl than with the detergents Triton X-100, hexadecyltrimethylammonium bromide, sodium deoxycholate, and sodium dodecylsulfate. APase activity was the least readily solubilized. Correlating the degree of solubilization for five marker enzymes with the types of stripping agents used and with the appearance of the membrane surface when examined by electron microscopy led to the suggestion that LAPase, GGTase, GGHase and maltase molecules are part of an interwoven surface layer of membrane proteins which can be disrupted by transamidation and transesterification reactions. APase appears to be more strongly associated with the intact lipid matrix than the bulk of the membrane protein.
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PMID:Ease of solubilization of five marker enzymes in three preparations of rat renal brush border membranes. 610 74


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