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)

Neutral alpha-glucosidase was partially purified from granular fractions isolated from guinea pig polymorphonuclear leukocytes (PMNL). The native enzyme had a high molecular weight, about 417,000, with a subunit of 43,000. The purified enzyme hydrolysed 4-methylumbelliferyl alpha-glucoside and maltose, but not isomaltose, trehalose, and glycogen. The enzyme was strongly inhibited by bromoconduritol and castanospermine, but only slightly by turanose. Monoclonal antibodies which can bind specifically to the enzyme were prepared by immunizing mice with the partially purified enzyme. Hybridomas producing the monoclonal antibodies were selected by an enzyme-linked immunosorbent assay. The seven monoclonal antibodies were found to react with the enzyme from PMNL, but not with the glycoprotein-processing alpha-glucosidase isolated from liver microsomes nor with the macrophage enzyme. The results indicated that PMNL contain a particulate neutral alpha-glucosidase enzymologically and immunologically distinct from other alpha-glucosidases.
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PMID:Neutral alpha-glucosidase in granule fractions from guinea pig polymorphonuclear leukocytes: enzymic characterization and comparative studies with monoclonal antibodies. 269 10

"Dihydroacarbose" (2), an alpha-D-glucosidase inhibitor having a pseudo-tetrasaccharide structure, was synthesized by reductive coupling of 4(3)-amino-1(1),6(1)-anhydro-2(1),3(1),2(2),3(2),6(2),2(3),3(3)-hepta-O- benzyl-4(3),6(3)-dideoxy-beta-maltotriose and 2D-(2,4/3,5)-2,3,4-tris(benzyloxy)-5-(trityloxymethyl)cyclohexa non e with sodium-cyanoborohydride. The former intermediate was prepared from a partially benzylated 1(1),6(1)-anhydro-beta-maltotriose, and the latter was prepared from a chiral, penta-substituted cyclohexene derived from D-glucose. The synthetic 2 was found to be a strong, non-competitive inhibitor (Ki = 1.13 x 10(-6) M) against small-intestinal sucrase of rat.
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PMID:Synthesis of "dihydroacarbose", an alpha-D-glucosidase inhibitor having a pseudo-tetrasaccharide structure. 269 42

The first steps of the biosynthetic pathway of high molecular weight polylactosamine-type glycopeptides from rat Zajdela hepatoma cells were studied by pulse-chase experiments, biochemical analysis and by inhibition of N-glycosylation. It is clear that this process involves firstly the transfer of a lipid-linked high-mannose oligosaccharide precursor to a protein moiety in a similar way to that of N-linked glycopeptides of a more common size range according to the classical 'cycle of dolichol'. In the presence of enzymes which are inhibitors of the processing of high-mannose oligosaccharide chains, this class of oligosaccharides was considerably increased, whereas polylactosamine chains and lower complex N-linked glycopeptides were concomitantly decreased in the same kinetics and the same ratio. As expected in the presence of N-methyldeoxynojirimycin, which is an alpha-glucosidase inhibitor, high-mannose oligosaccharides remained glycosylated and are mostly of the Glc1-3Man9GlcNAc type. In the presence of swainsonine, which is an alpha-mannosidase (EC 3.2.1.24) inhibitor, these chains were devoid of glucose residues. In addition, some chains displayed hybrid structures. It appears, therefore, that the first steps of the biosynthesis of polylactosamine-type and N-linked oligosaccharides of a more common size range proceed similarly and that differences between their biosynthetic pathways occur during the elongation phase, which leads to their final respective structures. Glycopeptides prepared from the cell surface by mild trypsin treatment as well as from entire cells, previously treated or not by processing inhibitors, display the same gel filtration patterns indicating that modifications in protein glycosylation do not prevent glycoprotein insertion into the cell membrane.
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PMID:Biosynthesis of high molecular weight polylactosamine-type glycopeptides in rat Zajdela hepatoma ascites cells. 271 99

Since they are found to be increased in lesions of acute necrotic ulcerative gingivitis or marginal periodontitis, agents for these diseases. In the present study, 38 pure cultured strains were obtained as a result of isolation and culture of samples collected from lesions of marginal periodontitis (periodontal pokets), and the biological and biochemical characteristics of these strains were investigated. 1) Light microscopy (including dark-field microscopy) and transmission electron microscopy (negative staining) were used for observation of the morphology and cellular structure of the strains. The cells had a spiral shape, and showed active movement. Based on the above findings the cultured strains were all confirmed to be spirochetes of small to medium size, being 0.08-0.24 micron in width. 2) Growth and motility of the strains were investigated on various types of culture medium. Intense growth and movement were noted in strains cultured in bovine liver exudate medium containing horse serum (pH 7.2) at 37 degrees C under anaerobic conditions produced by the evacuation-replacement method (95% N2, 5% CO2) for 3-7 days after inoculation. 3) Thirty-five strains were positive for indole production and decomposition of urea, mucin, hippuric acid and esculin. Production of hydrogen sulfied was observed in 31 strains. In decomposition tests for 17 carbohydrates, 17 strains were positive for galactose and 14 strains were positive for glucose, while 11 strains were positive for dextrin and 10 strains for fructose upon decomposition of soluble starch. Other carbohydrates were also decomposed by a few strains. 4) In an investigation of the production of alcohol and lower fatty acids, among the metabolic products detected by gas chromatography, a large amount of acetic acid and small amounts of ethanol, lactic acid, propionic acid, pyruvic acid were observed. 5) The results of enzyme activity tests using an API ZYM system indicated relatively high activities of esterase, esterase-lipase, alpha-glucosidase, alkaline phosphatase, trypsin and acid phosphatase.
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PMID:[Biological and biochemical characteristics of the oral spirochetes isolated from the focus of marginal periodontitis]. 276 48

Chemical galactosylation of human liver tissue lysosomal alpha-glucosidase was carried out. As a result of the modification some physicochemical properties of the enzyme were altered, while its stability and catalytic activity were maintained. An ability of the galactosylated alpha-glucosidase to interact with asialoglycoprotein receptor from mice liver tissue was studied in vitro. The reaction required Ca2+. A specific inhibitor of the receptor, N-acetyl galactosamine, as well as high concentrations of native glycoproteins and neoglycoproteins containing terminal galactose inhibited the receptor binding of the 125I-galactosylated alpha-glucosidase. Native alpha-glucosidase was not bound with the receptor. Antireceptor antibodies inhibited similarly binding of both native ligand, asialoorosomucoid and the galactosylated alpha-glucosidase. These data on specific interaction between the galactosylated form of alpha-glucosidase and asialoglycoprotein receptor are discussed in connection with the problem of directed transport of the enzyme into liver parenchymatous cells by means of receptor-dependent endocytosis, which may be of importance in development of enzymotherapy of hereditary lysosomal enzymopathies.
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PMID:[Chemical galactosylation of acid alpha-glucosidase to provide directed transport of the enzyme into lysosomes of liver parenchymal cells]. 282 27

Toluene-treated cells of Streptococcus bovis JB1 phosphorylated cellobiose, glucose, maltose, and sucrose by the phosphoenolpyruvate-dependent phosphotransferase system. Glucose phosphorylation was constitutive, while all three disaccharide systems were inducible. Competition experiments indicated that separate phosphotransferase systems (enzymes II) existed for glucose, maltose, and sucrose. [14C]maltose transport was inhibited by excess (10 mM) glucose and to a lesser extent by sucrose (90 and 46%, respectively). [14C]glucose and [14C]sucrose transports were not inhibited by an excess of maltose. Since [14C]maltose phosphorylation in triethanolamine buffer was increased 160-fold as the concentration of Pi was increased from 0 to 100 mM, a maltose phosphorylase (Km for Pi, 9.5 mM) was present, and this activity was inducible. Maltose was also hydrolyzed by an inducible maltase. Glucose 1-phosphate arising from the maltose phosphorylase was metabolized by a constitutive phosphoglucomutase that was specific for alpha-glucose 1-phosphate (Km, 0.8 mM). Only sucrose-grown cells possessed sucrose hydrolase activity (Km, 3.1 mM), and this activity was much lower than the sucrose phosphotransferase system and sucrose-phosphate hydrolase activities.
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PMID:Transport and phosphorylation of disaccharides by the ruminal bacterium Streptococcus bovis. 282 69

The human colon carcinoma cell line HT-29 differentiates into functional enterocytes upon replacement of glucose by galactose in the culture medium. Since the differentiation of other types of cells is associated with the modulation of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) receptor concentrations and since enterocytes are classical target cells for 1,25(OH)2D3 we have examined the HT-29 cells to determine whether the differentiated and undifferentiated stages could be directly linked to the presence of 1,25(OH)2D3 receptors. HT-29 cells were grown in Dulbecco's modified medium containing 10% fetal calf serum (FCS) and glucose or galactose. Cell differentiation was assessed by measuring the brush border hydrolase, maltase. 1,25(OH)2D3 receptors were studied in the cells after 48 h without FCS. Nuclear uptake was measured in intact dispersed cells and the receptor protein was further characterized by vitamin D metabolite binding specificity, sucrose density gradient analysis and binding to DNA-cellulose. Maltase activity was 5-fold greater in differentiated HT-29 cells than in undifferentiated cells. Scatchard analysis showed a highly specific saturable (9500 sites per cell) high affinity (2 x 10(-10) M), binding of 1,25(OH)2D3 in undifferentiated cells. This receptor-like protein sedimented at 3.3S, bound to and eluted from DNA-cellulose and had all the characteristics of a 1,25(OH)2D3 receptor. No specific binding was detected in differentiated HT-29 cells. The presence of 1,25(OH)2D3 receptors in undifferentiated HT-29 cells implies that these cells are targets for vitamin D. The maltase activity increased significantly when undifferentiated cells were exposed to 1,25(OH)2D3 for 5-6 days, indicating that the hormone can promote differentiation of HT-29 cells. These results demonstrate that HT-29 cells can provide a new model for studying steroid receptor regulation and cell differentiation.
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PMID:Human colon cell line HT-29: characterisation of 1,25-dihydroxyvitamin D3 receptor and induction of differentiation by the hormone. 283 36

Intracellular transport of two lysosomal enzymes, acid alpha-glucosidase and beta-hexosaminidase, was analyzed in human fibroblasts. The precursors of beta-hexosaminidase in normal fibroblasts were released from the membrane fraction by treatment with mannose 6-phosphate, but the precursor of alpha-glucosidase was not. Percoll density gradient centrifugation revealed a normal amount of acid alpha-glucosidase activity in heavy lysosomes in I-cell disease fibroblasts despite impaired maturation and defective phosphorylation, and beta-hexosaminidase activity was markedly reduced in lysosomes. It was concluded that the membrane-bound precursor of acid alpha-glucosidase is transported to lysosomes by a phosphomannosyl receptor-independent system although the enzyme lacks the recognition marker for the phosphomannosyl receptor and processing of an intermediate form to mature forms does not occur in this disease.
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PMID:Intracellular transport of acid alpha-glucosidase in human fibroblasts: evidence for involvement of phosphomannosyl receptor-independent system. 284 24

The "high-mannose" glycosylated forms of aminopeptidase N (EC 3.4.11.2), maltase-glucoamylase (EC 3.2.1.20), and sucrase-isomaltase (EC 3.2.1.48, EC 3.2.1.10) have been purified. The high-mannose glycosylated form of sucrase-isomaltase was found to have a lower specific activity than the complex glycosylated form, whereas no difference was observed for the two other enzymes. The change in glycosylation from high-mannose to complex form thus seems to be of importance for the enzymatic activity of sucrase-isomaltase either by direct structural involvement or by a general stabilization effect on the protein conformation.
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PMID:Enzymatic activity of "high-mannose" glycosylated forms of intestinal microvillar hydrolases. 286 40

Atrophy of the small intestinal mucosa is functionally characterized by a reduction in non-electrolyte transport in vivo. In order to elucidate the cellular defect being responsible for this malabsorption, we have studied the Na+-dependent D-glucose accumulation as well as the activities of aminopeptidase M and maltase in brush border membrane vesicles prepared from jejunal self-emptying blind loops and corresponding intestinal segments of sham-operated control rats. Membrane vesicles from atrophic mucosa did not show any differences in D-glucose uptake or in enzyme activities when compared with those derived from normal intestine. Thus it is unlikely that the impaired non-electrolyte absorption in the atrophic mucosa in vivo is due to a defect in cellular transport processes. It is more probable that the functional impairment is the result of the diminished absorptive surface in this pathophysiological condition.
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PMID:[Functional characterization of luminal enterocyte membranes of the small intestine mucosa using isolated brush border membranes]. 288 Apr 30


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