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 large amount of lysosomal acid hydrolases was released into the medium by Tetrahymena pyriformis strain W during growth. An extracellular lysosomal acid alpha-glucosidase has been purified 500-fold with a 41% yield to homogeneity, as judged by polyacrylamide gel electrophoresis. It was found to be a glycoprotein and to consist of a single 110,000-dalton polypeptide chain. The carbohydrate content of the alpha-glucosidase was equivalent to 2.8% of the total protein content, and the oligosaccharide moiety was composed of mannose and N-acetylglucosamine in a molar ratio of 6.7:2. The optimal pHs for hydrolysis of maltose and p-nitrophenyl-alpha-glucopyranoside, maltose, isomaltose, and glycogen were 1.1 mM, 2.5 mM, 33.0 mM, and 18.5 mg/ml, respectively. This purified enzyme appears to have alpha-1,6-glucosidase as well as alpha-1,4-glucosidase activity. Turanose has a noncompetitive inhibitory effect on the hydrolysis of maltose. The antibody raised against Tetrahymena acid alpha-glucosidase inhibited the hydrolysis of all substrates tested. These properties of Tetrahymena acid alpha-glucosidase were found to be similar to those of the human liver lysosomal alpha-glucosidase.
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PMID:Purification and characterization of lysosomal alpha-glucosidase secreted by eukaryote Tetrahymena. 392 1

The enzymic hydrolysis of glycosyl fluorides is conveniently followed by using a pH-stat. Reactions involving glucosyl or galactosyl fluorides can also be followed by using glucose oxidase or galactose oxidase respectively. The pH-stat allows the rapid assay of intestinal alpha-glucosidase in crude homogenates. Use of glycosyl fluorides as substrates for glycosidases facilitates the polarimetric or g.l.c. determination of the anomeric nature of the initial product of hydrolysis. Hydrolysis by fungal amyloglucosidase proceeds with inversion of configuration whereas that by yeast and rat intestinal alpha-glucosidase, coffee-bean alpha-galactosidase and almond emulsin beta-glucosidase proceeds with retention of configuration. beta-d-Glucopyranosyl azide was not a detectable substrate for almond emulsin beta-d-glucosidase.
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PMID:The hydrolysis of glycosyl fluorides by glycosidases. Determination of the anomeric configuration of the products of glycosidase action. 512 11

The recent findings that alpha-glucosidase from human kidney was identical with one component (F1) of the alpha-glucosidases found in human urine suggested the idea that this enzyme might originate in the kidneys. The present study was performed to test this idea by immunological methods. Urine alpha-glucosidase F1 was isolated in the electrophoretically homogeneous state, and the antibody prepared in rabbits was purified by affinity chromatography after the antisera were fractionally precipitated with ammonium sulfate and chromatographed on diethylamino ethyl (DEAE)-cellulose. The staining of human kidney tissue sections was performed by the indirect method, using alpha-glucosidase F1 antibody and fluorescein-conjugated anti-rabbit immunoglobulin goat sera. The proximal convoluted portion (proximal tubules) with brush border and Henle's loops (late proximal) were stained clearly. Preincubation of intact antibody with purified antigen prevented specific staining of the proximal convoluted portion and Henle's loops. In contrast, all other tissues of kidney were stained less positively or negatively. These results indicate that alpha-glucosidase F1 originates in the kidney, and that glucosidase is specifically localized in the proximal convoluted portion and Henle's loops.
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PMID:On the origin of alpha-glucosidase in human urine. 618 15

Particulate membrane fractions from calf liver catalyze the release of glucose from GlcNAc2-Man9-Glc1-3-oligosaccharides. Maximal oligosaccharide-glucosidase activity was obtained at pH 6.2 and a detergent concentration of 0.5% Triton X-100. This activity could be distinguished from non-specific alpha-glucosidase activity on the basis of different pH-dependence and lack of activation by detergent. The relative rates for the hydrolysis of the Glc3-, Glc2-, and Glc1-oligosaccharide, estimated from the initial velocity, was 1:12:3. There is no significant difference in the enzyme activity towards free, peptide-bound, or lipid-linked oligosaccharide. Nojirimycin and 1-deoxynojirimycin were strong inhibitors of microsomal oligosaccharide-glucosidases. Hydrolysis of Glc3-oligosaccharide was inhibited by 50% at concentrations of 0.16 mM and 2 microM, respectively. Hydrolysis of the Glc2- and Glc1-oligosaccharide was inhibited to a somewhat lower extent, suggesting the presence of at least two glucosidases, one acting on Glc3- and one acting on Glc1- and Glc2-oligosaccharide.
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PMID:Inhibition by nojirimycin and 1-deoxynojirimycin of microsomal glucosidases from calf liver acting on the glycoprotein oligosaccharides Glc1-3Man9GlcNAc2. 621 40

Acarbose is known to inhibit glucoamylase, maltase and sucrase. Our aim was to test whether it would also inhibit glucosyltransferase (GTF), to determine the type of inhibition and to compare the inhibitor potency of acarbose with that of nojirimycin and deoxynojirimycin, two other glucosidase inhibitors. Enzyme inhibition was measured either by chemical assay or by incorporation of radioactivity into product. Acarbose effectively inhibited the synthesis of polysaccharide by GTF from strains of Streptococcus mutans and Streptococcus sanguis, but not by fructosyltransferase from Streptococcus salivarius. Acarbose and 1-deoxynojirimycin were more potent inhibitors of GTF than maltose, nojirimycin or various amino sugars. The mechanism of action of these compounds is consistent with competitive inhibition.
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PMID:Inhibition by acarbose, nojirimycin and 1-deoxynojirimycin of glucosyltransferase produced by oral streptococci. 622 60

Certain effects of glucagon administration on newborn rat hepatocytes were studied using biochemical assays, electron microscopy and quantitative morphometry. Glucagon accelerated the normal postnatal hyaloplasmic glycogen breakdown and the lysosomal glycogen breakdown. The glucagon-treated animals showed an increased activity of the enzyme, acid a 1,4 glucosidase (maltase). The results suggest that the catabolism of lysosomal glycogen is controlled by those agents that regulate the catabolism of hyaloplasmic glycogen and that this control is mediated through changes in the activity of the lysosomal acid a 1,4 glucosidases.
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PMID:An electron microscopic and biochemical study of the effects of glucagon on newborn rat hepatocytes. 639 4

In order to study the influence of biliary secretions on the in situ kinetic data of brush border disaccharidases in relation to small intestinal villus-crypt architecture, an anastomosis was constructed between the common bile duct, which had been divided before its entrance into the pancreatic head, and the ileum in adult female Wistar rats. Simple attachment of the terminal ileum to the liver hilum was performed in the controls. Six weeks after the operation, tissue sections were prepared from duodenum and ileum of biliary-diverted and control animals (n = 5 in each group) and examined by section biochemistry and morphometry. In both groups the apparent Vmax values of neutral alpha-glucosidase and lactase/beta-glucosidase, measured at the villus base and at its apex, and the villus height were decreased from the duodenum towards the distal ileum. After biliary diversion to the ileum, an increase in villus height ensued in this segment, and the increasing gradient of glucosidase activity towards the villus apex, as seen in the ileum of the controls, was no longer detectable. In the duodenum, however, villus height remained unaltered and the in situ activity of the disaccharidases was increased at both villus sites when compared with the controls. The results indicate different effects of bile on mucosal morphology and function in the proximal and distal small intestine.
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PMID:Effects of biliary diversion to the ileum on the in situ disaccharidase activities of duodenal and ileal mucosa in the rat: a study on enzyme kinetics in tissue sections. 641

Fluorescent Pseudomonas species (P. aeruginosa, P. fluorescens, P. putida) were tested for the presence of glycosidase activities (alpha-D-glucosidase, beta-D-glucosidase, alpha-D-galactosidase, beta-D-galactosidase, beta-xylosidase, alpha-D-mannosidase, alpha-L-fucosidase, beta-L-fucosidase, beta-D-glucuronidase and N-acetyl-beta-D-glucosaminidase). Some of the investigated glycosidases were always absent, while N-acetyl-beta-D-glucosaminidase was constantly present in all strains; 3 glycosidase activities were observed in association or separately. Serotype O11 of P. aeruginosa was found to be homogeneous with respect to some of those enzymatic activities. Search for beta-D-galactosidase, alpha-D-glucosidase and beta-D-glucosidase may be of diagnostic value in epidemiologic studies of P. aeruginosa.
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PMID:[Detection of glycosidases in Pseudomonas of the fluorescent group: relation between serotype and glycosidase activities in P. aeruginosa]. 642 62

Bacillus anthracis could be distinguished from the taxonomically related species B. cereus, B. mycoides, and B. thuringiensis by a comparison of glycosidase activities. All the bacilli tested possessed alpha-glucosidase activity, as evidenced by the hydrolysis of p-nitrophenyl-alpha-D-glucoside. In B. anthracis, the glucosidase activity could be enhanced by the addition of agents which damage cellular surface structures. Treatment of B. anthracis strains with toluene. Triton X-100, or mutanolysin or cellular disruption by sonication resulted in higher rates of alpha-glucoside hydrolysis than were accomplished by cells suspended in buffer. It is suggested that intact B. anthracis cells have a limited permeability to the glucosidase substrate. In contrast to the results obtained for B. anthracis, Triton X-100 markedly diminished the enzymatic hydrolysis of p-nitrophenyl-alpha-D-glucoside by strains of B. cereus, B. mycoides, and B. thuringiensis. Triton X-100 also enhanced the alpha-maltosidase activity of B. anthracis but not that of the other bacilli. B. mycoides possessed an apparently inducible N-acetylglucosaminidase although the enzyme was absent in B. anthracis. The glucosaminidase was inducible in the presence of p-nitrophenyl-N-acetylglucosamine in the absence of conventional nitrogen sources. Chloramphenicol prevented the induction of the glucosaminidase in B. mycoides. In several B. cereus and all B. thuringiensis strains, the glucosaminidase was constitutive. The results suggest a means for the rapid laboratory differentiation of B. anthracis from other closely related bacilli. Assays for alpha-glucosidase and alpha-maltosidase, in the presence and absence of Triton X-100, can be used to distinguish B. anthracis from B. cereus, B. mycoides, and B. thuringiensis. Similarly, the hydrolysis of p-nitrophenyl-beta-N-acetylglucosamine induced by B. mycoides but not by B. anthracis provides an additional means for differentiating these similar bacilli.
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PMID:Glycosidase activities of Bacillus anthracis. 642 87

Crude membrane fractions from Volvox carteri in the presence of detergent and metal complexing agent catalyze the transfer of glucose from dolichyl phosphate glucose to branched dolichyl diphosphate chitobiosyl pentamannoside Dol-PP-(GlcNAc)2-(Man)5, a known intermediate of the lipid-mediated pathway of N-glycosylation of proteins, resulting in the formation of Dol-PP-(GlcNAc)2-(Man)5-(Glc)1. Under the various conditions tested, neither Dol-P-Man nor other known mannosyl donors of the nucleoside-activated or lipid-activated type can serve as donor molecules for the elongation of the lipid-linked heptasaccharide. On the other hand, calf liver microsomes in similar experiments mannosylated the heptasaccharide further with Dol-P-Man up to a nonamannoside, Dol-PP-(GlcNAc)2-(Man)9. A direct glucosylation of the acceptor, however, with Dol-P-Glc failed in this system. The (GlcNAc)2-(Man)5-(Glc)1, obtained after mild acid hydrolysis of the above glycolipid is not significantly split by an unspecific alpha-glucosidase from yeast. However, Volvox microsomes liberated most of the glucose indicating a specific glucosidase in the membranes of the alga. This enzyme does not act on (GlcNAc)2-(Man)9-(Glc)1, the usual protein-linked carbohydrate intermediate of trimming processes of N-glycosidic glycoproteins. The data on glycolipid formation let us postulate that in Volvox the normal N-glycosylation pathway differs from that found in higher plants and animals either by a lack of evolution or by mutation in the genes coding for the mannosyl transferases involved.
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PMID:Evidence for an incomplete dolichyl-phosphate pathway of lipoglycan formation in Volvox carteri f. nagariensis. 669 21


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