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)

Some diets exert a considerable influence on porphyrin metabolism and induction of microsomal liver enzymes in experimental porphyria induced by hexachlorobenzene (HCB). As HCB and its metabolites come into direct contact with intestinal mucosa, this study investigated the changes in the activities of intestinal disaccharidases and gamma-glutamyl transferase in a model of HCB-induced porphyria. The effects of different diets on enzymatic activities during HCB intoxication were also studied. HCB was administered by gastric tube at 3.5 mmol/kg body weight daily for 90 and 61 days. HCB intoxication strongly diminished the activities of intestinal lactase, maltase, sucrase, cellobiase and trechalase. Carbohydrate diets (with 78 weight % glucose or starch), given simultaneously with HCB treatment, exerted a protective effect on disaccharidase activities. These regimens maintained cellobiase and trechalase within the normal levels and even increased maltase. High-fat/high-protein diets (with 30% either butter or sunflower oil and 31% casein) aggravated the decrease of all disaccharidases. In contrast with the decrease in disaccharidase activity, intestinal gamma-glutamyl transferase was increased, suggesting multiple mechanisms for the action of HCB intoxication on the intestinal enzyme system. Diet had a pronounced modifying effect.
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PMID:Changes in some intestinal enzyme activities in experimental hexachlorobenzene-induced porphyria and modifying effects of diet. 288 67

A neutral maltase immunologically similar to this of kidney exist in human granulocytes. We have studied some kinetic properties of this enzyme on a microsomal fraction of granulocytes. Its optimal pH is very closed of 6.8 and this enzyme, highly specific for maltose, hydrolysis very weakly the nigeriosis. Maltotriose, maltotetraose and maltopentanose are inhibitors of this enzyme, which is not inhibited by all disaccharides studied.
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PMID:[Substrate specificity and kinetic properties of neutral maltase of human granulocytes]. 296 58

Early events in the biosynthesis of alpha-glucosidase (EC 3.2.1.20) were studied in a wheat-germ cell-free translation system, using control and mutant RNA. In vitro, the primary translation product of the alpha-glucosidase mRNA is a 100 kDa protein. When canine microsomal membranes are added to the translation system, the nascent alpha-glucosidase precursor is cotranslationally transported across the microsomal membranes, yielding a 110 kDa glycosylated form. This protein has the same electrophoretic characteristics as the alpha-glucosidase precursor observed after in vivo labeling of control fibroblasts. Inhibition of glycosylation in vivo by tunicamycin or deglycosylation of the in vivo synthesized alpha-glucosidase precursor by glycopeptidase F reveals a core protein similar in molecular mass to the primary translation product. Total RNA from a patient with the adult form of glycogenosis type II is not able to direct the synthesis of normal amounts of alpha-glucosidase in vitro. Northern blot analysis of the RNA, using cloned alpha-glucosidase cDNA sequences as a probe, demonstrates that in this patient the amount of the 3.4 kb alpha-glucosidase mRNA is highly reduced. The results indicate that the synthesis or stability of the mRNA is affected.
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PMID:Cell-free translation of human lysosomal alpha-glucosidase: evidence for reduced precursor synthesis in an adult patient with glycogenosis type II. 331 2

The role of lysosomal enzyme acid alpha-glucosidase in fetal lung development was investigated with the aid of a specific inhibitor, the pseudosaccharide acarbose. The drug was added to a Waymouth culture medium of fetal rat lung explants cultivated for 48 h from gestational stage 19.5 days, an in vitro system previously shown to allow morphological and biochemical maturation of alveolar epithelium. Glycogenolysis was reduced by 40% as compared with tissue cultivated on control medium, which means that alpha-glucosidase could account for as much as 40% of fetal lung glycogenolysis, the remaining 60% being presumably achieved by cytosolic phosphorylase and by a microsomal neutral alpha-glucosidase. By the same time, the increase of phospholipids of surfactant fraction extracted from cultivated explants was partially inhibited: total and saturated phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol were about 30-40% lower than in lungs cultivated on control medium. It should be emphasized that DNA concentration and increases in non-surfactant phospholipids were unchanged by the drug. alpha-Glucosidase activity was evidenced in the lysosomal fraction, in the microsomal fraction and, although in lower amounts, in the surfactant fraction extracted from term fetal lung. The results suggest that lysosomal alpha-glucosidase plays a major role in lung maturation and could facilitate glycogenolysis for the specific use of glycogen stores in providing substrates for surfactant phospholipid biosynthesis.
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PMID:Role of alpha-glucosidase in fetal lung maturation. 353 7

We have previously partially purified, characterized, and chromosomally mapped a human isozyme of alpha-glucosidase which is active at neutral pH. This isozyme appears as a doublet of enzyme activity on native gel electrophoresis and was termed neutral alpha-glucosidase AB. We now report genetic and biochemical evidence that neutral alpha-glucosidase AB is synonymous with the glycoprotein processing enzyme glucosidase II. We have found that a mutant mouse lymphoma line which is deficient in glucosidase II is also deficient in neutral alpha-glucosidase AB, as defined electrophoretically and quantitatively (less than 0.5% of parental). In contrast, both mutant and parental cell lines exhibited several lysosomal hydrolases which are processed by glucosidase II. We have also further purified the human neutral alpha-glucosidase A component of neutral alpha-glucosidase AB 740-fold from placenta in order to compare its biochemical properties with those described for rat liver and pig kidney glucosidase II. Both glucosidase II and neutral alpha-glucosidase AB are high-molecular mass (greater than 200,000 dalton) anionic glycoproteins which bind to concanavalin A, have a broad pH optima (5.5-8.5), and have a similar Km for maltose (4.8 versus 2.1 mM) and the artificial substrate 4-methylumbelliferyl-alpha-D-glucopyranoside (35 versus 19 microM). Similar to human neutral alpha-glucosidase AB, purified rat glucosidase II migrates as a doublet of enzyme activity on native gel electrophoresis. Although rat glucosidase II has been reported to have a subunit size of 67 kDa, pig glucosidase II has been found to have a subunit size of 100 kDa, like the 98-kDa major protein in purified human neutral alpha-glucosidase A. Although we have not demonstrated that neutral alpha-glucosidase AB is microsomal nor that it hydrolyzes the natural substrate of glucosidase II, we believe that the genetic evidence is compelling for and the biochemical data consistent with the hypothesis that neutral alpha-glucosidase AB and glucosidase II are synonymous. These and previous results would localize glucosidase II to the long arm of human chromosome II.
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PMID:Identity of neutral alpha-glucosidase AB and the glycoprotein processing enzyme glucosidase II. Biochemical and genetic studies. 388 23

A technique for the isolation of intact brush borders from rabbit renal cortex was evaluated. The procedure was monitored by phase and electron microscopy and marker enzymes, i.e. ATP:NMN adenylyl transferase, nuclear; cytochrome oxidase, mitochondrial; beta-glucuronidase, lysosomal; and glucose-6-Pase, microsomal; and indicated an essentially pure preparation of brush borders. The disaccharidase, trehalase, previously reported in renal tubules, was localized uniquely in brush borders. Maltase was also found; the specific activities of the two enzymes in the brush borders were increased 10- to 20-fold. Other disaccharidases, such as sucrase, isomaltase, lactase, and cellobiase, were absent. It is suggested that trehalase and maltase are appropriate candidates for marker enzymes of the renal brush border. Isolated brush borders possessed a ouabain-sensitive (Na(+) + K(+)) ATPase, an oligomycin-insensitive Mg(++) ATPase, and a Ca(++)-activated ATPase. Alkaline phosphatases, dephosphorylating beta-glycero-P, and trehalose-6-P were also present. The specific activities of these enzymes were increased three-to-five fold in the brush-border preparations; however, activities were found in other subcellular fractions of the renal cortex. Hexokinase, although evident in the isolated brush border, was found prominently associated with other membranous fractions. Phosphoglucomutase and UDPG pyrophosphorylase were localized in the soluble fraction of the renal cortex.
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PMID:Isolation and biochemical characterization of brush borders from rabbit kidney. 425 Jun 12

In the pigeon, 70-80% of the activities of maltase (alpha-D-glucoside glucohydrolase EC 3.2.1.20), sucrase (alpha-glucohydrolase, EC 3.2.1.48), isomaltase (dextran 6-alpha-D-glucan hydrolase, EC 3.2.1.10) and glucoamylase (1,4-alpha-D-glucan glucohydrolase, EC 3.2.1.3) were found to be localized in the brush-border membrane of intestinal epithelial cells. Of the total glycosidase activities in the mucosal homogenate, nearly 60 to 70% were recovered in the microsomal (105 000 X g) fraction, about 30% in the mitochondrial (22 000 X g) fraction and less than 5% from the cytosol (105 000 X g supernatant) fraction. The hydrolases were solubilized by digestion with papain but not with trypsin, and the phosphate ion had a protective effect in the solubilization. Amongst detergents, Triton X-100 but not sodium deoxycholate, was found to truly solubilize these enzymes.
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PMID:Studies on the intestinal disaccharidases of the pigeon. II. Subcellular localization and solubilization. 618 28

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

Bloodstream forms of Trypanosoma brucei have been screened for the presence of enzymes that could serve as markers for the plasma membrane, flagellar pocket, lysosomes, endoplasmic reticulum and Golgi apparatus in order to study the subcellular organization of the digestive system of the parasite. Acetylesterase, acid DNase, acid phosphatase, acid phosphodiesterase, acid proteinase, acid RNase, alanine aminotransferase, galactosyl transferase, alpha-glucosidase, inosine diphosphatase and alpha-mannosidase were partially characterized and their assays optimized for pH-dependent activity, linearity of reaction with respect to incubation time and enzyme concentration, and the effect of inhibitors and activators. The association of these enzymes with particulate material and the presence of structural latency were investigated. Acid proteinase and alpha-mannosidase are particle-bound and latent in cytoplasmic extracts; they can be activated and solubilized in part by Triton X-100. Similar results were obtained for acid phosphatase, acid phosphodiesterase and inosine diphosphatase. Neutral alpha-glucosidase, though partly sedimentable, does not show latency and is readily solubilized by the detergent. Galactosyl transferase is firmly membrane-bound even in the presence of 0.1% Triton X-100. Cell fractionation by differential centrifugation and density equilibration on sucrose gradients revealed that both alpha-mannosidase and acid proteinase are associated with organelles that band at a density of about 1.20 g/cm3. Inosine diphosphatase, galactosyl transferase, acid phosphatase and acid phosphodiesterase sediment predominantly as microsomal constituents equilibrating at densities between 1.13 and 1.15 g/cm3. In addition, inosine diphosphatase and galactosyl transferase exhibit considerable activity at higher densities (1.18-1.25 g/cm3). Neutral alpha-glucosidase is mainly recovered in the nuclear and microsomal fraction; its particulate part equilibrates as a single band at rho = 1.22 g/cm3. Acetylesterase and acid DNase are largely soluble, whereas acid RNase does not produce distinct sedimentation and banding profiles. In intact cells, neutral alpha-glucosidase and acid phosphatase appear to be highly accessible to their substrates. It is tentatively concluded that (a) acid proteinase and alpha-mannosidase are lysosomal enzymes, (b) acid phosphatase and acid phosphodiesterase are associated with the flagellar pocket and part of the former enzyme probably with the endoplasmic reticulum, (c) galactosyl transferase is a constituent of the Golgi apparatus, and (d) alpha-glucosidase may serve as a marker for the plasma membrane. Inosine diphosphatase may also be derived from the latter structure.
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PMID:Subcellular fractionation of Trypanosoma brucei bloodstream forms with special reference to hydrolases. 624 76

Resident peritoneal macrophages of the mouse, cultivated for 3 d, have been studied by quantitative subcellular fractionation using differential centrifugation and density equilibration in linear gradients of sucrose. Density equilibration experiments were carried out on untreated cytoplasmic extracts, on cytoplasmic extracts treated with digitonin or sodium pyrophosphate, and on cytoplasmic extracts derived from cells cultivated for 24 h in the presence of Triton WR-1339. The enzyme distributions obtained distinguished six typical behaviors characteristic of distinct subcellular entities. Acid alpha-galactosidase and other acid hydrolases displayed the highest average velocity of sedimentation and equilibrium density. Culturing in a medium that contained Triton WR-1339 markedly decreased their density, most likely as a result of Triton WR-1339 accumulation within lysosomes. Cytochrome c oxidase and the sedimentable activity of malate dehydrogenase showed a narrow density distribution centered around 1.17, very similar under all the experimental situations; their rate of sedimentation fell within the range expected for mitochondria. Catalase was particle-bound and exhibited structure-linked latency (80 percent); it was released in soluble and fully active form by digitonin, but this required a much higher concentration than in the case of lysosomal enzymes. Differences relative to all the other enzymes studied suggest the existence of a particular species of organelles, distinctly smaller than mitochondria, and possibly related to peroxisomes. Many enzymes were microsomal in the sense that the specific activities, but not the yields, were greater in microsomes than in other fractions obtained by differential centrifugation. These enzymes were distinguished in three groups by their properties in density equilibration experiments. NAD glycohydrolase, alkaline phosphodiesterase I, and 5'-nucleotidase had low equilibrium densities but became noticeably more dense after addition of digitonin. The other microsomal enzymes were not shifted by digitonin, in particular N-acetylglucosaminyltransferase and galactosyltransferase, which otherwise equilibrated at the same position in the gradient. We assign the digitonin-sensitive enzymes to plasma membranes and possibly to related endomembranes of the cells, and the two glycosyltransferases to elements derived from the Golgi apparatus. Finally, alpha-glucosidase, sulphatase C, NADH cytochrome c reductase, NADPH cytochrome c reductase, and mannosyltransferase, equilibrated at a relatively high density but were shifted to lower density values after addition of sodium pyrophosphate. These properties support their association with elements derived from the endoplasmic reticulum.
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PMID:Analytical subcellular fractionation of cultivated mouse resident peritoneal macrophages. 630 Feb 79


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