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)

In lamellar bodies isolated from adult human lung at least two acid alpha-glucosidases are present: one similar to the lung lysosomal alpha-glucosidase, and another lamellar body-specific isoenzyme. In the present study we measured the activity of this lamellar body-specific alpha-glucosidase and of lysosomal alpha-glucosidase in a patient with an inherited deficiency of lysosomal alpha-glucosidase. The activity of the lamellar body-specific alpha-glucosidase was not affected in the patient, whereas the lysosomal alpha-glucosidase activity was strongly depressed. The results strongly suggest that the lysosomal alpha-glucosidase and the lamellar body-specific alpha-glucosidase are different gene products.
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PMID:Genetic relationship between lysosomal and lamellar body-specific alpha-glucosidases in human lung. 353 Mar 34

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

A sensitive and specific immunological assay for detection of human lysosomal alpha-glucosidase was developed using a mouse monoclonal antibody incorporated into a biotin-avidin amplified ELISA. The immunoassay was more than 60 times more sensitive than the currently used enzymatic assay for alpha-glucosidase activity using a fluorimetric substrate. This methodology provides an alternative approach with increased sensitivity for screening individuals for alpha-glucosidase deficiency.
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PMID:Detection of human acid alpha-glucosidase in fibroblasts using monoclonal antibodies in a biotin-avidin amplified ELISA. 390 82

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

In the present investigation, we have demonstrated that three lysosomal-type hydrolases, alpha-glucosidase, alpha-mannosidase and a phosphatase, are present in lamellar bodies isolated from adult human lung. The hydrolase activities that were studied, all showed an acidic pH optimum, which is characteristic for lysosomal enzymes. The properties of acid alpha-glucosidase in the lamellar body fraction and that in the lysosome-enriched fraction were compared. Using specific antibodies against lysosomal alpha-glucosidase from human placenta, two alpha-glucosidases could be distinguished in the lamellar body fraction: one with a high affinity to the antibodies as found in the lysosome-enriched fraction and another with a much lower affinity. Both forms showed an acidic pH optimum. The same heterogeneity of alpha-glucosidase in the lamellar body fraction could be observed using immobilized concanavalin A. The lectin was able to precipitate nearly all alpha-glucosidase activity of the lysosome-enriched fraction. In contrast, 30% of the alpha-glucosidase activity in the lamellar body fraction was not precipitable. Furthermore, the lamellar body alpha-glucosidase with the low antibody affinity could not be bound to concanavalin A. The results suggest that lamellar bodies contain at least two acid alpha-glucosidases: one similar to the lung lysosomal alpha-glucosidase, and another lamellar body-specific isoenzyme with a different immunoreactivity and lectin affinity. The lamellar body-specific alpha-glucosidase should prove useful as a lamellar body-specific marker enzyme.
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PMID:A specific acid alpha-glucosidase in lamellar bodies of the human lung. 393 64

A two-step procedure is described for the isolation of lysosomal alpha-glucosidase from human urine. In the second step, affinity chromatography on Sephadex G-100, two fractions with acid alpha-glucosidase activity were obtained. Fraction I contained alpha-glucosidase of Mr 109000, whereas fraction II contained components of Mr 76000 and 70000. alpha-Glucosidase in fraction I had an Mr similar to that of the precursor of alpha-glucosidase detected in the medium of fibroblasts after labelling with [14C]leucine. The components in fraction II had Mr identical to those of the mature forms of alpha-glucosidase found in placenta or cultured human skin fibroblasts. alpha-Glucosidase in fraction I contained mannose 6-phosphate (3.5 mol/mol polypeptide). No mannose 6-phosphate was present in the components in fraction II. Fraction I, but not fraction II, was avidly endocytosed by alpha-glucosidase-deficient cultured human skin fibroblasts. Endocytosis of fraction I was inhibited by mannose 6-phosphate. The pH optimum and Km values for p-nitrophenyl alpha-glucoside, maltose and glycogen of fractions I and II alpha-glucosidase were almost identical. However, the activity with glycogen relative to that of either p-nitrophenyl alpha-glucoside or maltose was lower in fraction I than in fraction II. It is concluded that fraction I consists of the precursor form of alpha-glucosidase and fraction II of the mature forms of the enzyme. The importance of urine as a source of precursors of lysosomal enzymes is discussed.
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PMID:Isolation and characterization of a precursor form of lysosomal alpha-glucosidase from human urine. 636 53

The maturation of lysosomal alpha-glucosidase in cultured human skin fibroblasts was studied using a monoclonal antibody that distinguishes between the precursor and mature forms of the enzyme. Monoclonal antibodies against alpha-glucosidase isolated from placenta were produced by the hybridoma technique [Hilkens et al. (1981) Biochim. Biophys. Acta 678, 7-11]. One of these monoclonal antibodies, that synthesized by clone 43G8, reacts with the mature forms, but not with the precursor form of alpha-glucosidase isolated from urine. By means of pulse-labelling studies, it could be shown that monoclonal antibody 43G8 does not react with either the intracellular or the secreted precursor of alpha-glucosidase from cultured human skin fibroblasts. However, the antibody does react with the intermediate and mature forms of alpha-glucosidase. Endocytosis of the precurosor of alpha-glucosidase from urine by fibroblasts is followed by its conversion to a form with lower molecular mass. After endocytosis urinary precursor alpha-glucosidase is converted to a form that binds to monoclonal antibody 43G8. The t 1/2 for this conversion is 2 h. The conversion is inhibited by addition of leupeptin to the culture medium. It is concluded that a thiol proteinase is involved in the maturation of alpha-glucosidase in fibroblasts and the appearance of the antigenic determinant for 43G8.
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PMID:Use of a monoclonal antibody to distinguish between precursor and mature forms of human lysosomal alpha-glucosidase. 636 54

Castanospermine (1,6,7,8-tetrahydroxyoctahydroindolizine) was tested against a variety of commercially available glycosidases and found to be a potent inhibitor of almond emulsin beta-glucosidase, and also to inhibit fungal beta-xylosidase. This alkaloid was inactive on yeast alpha-glucosidase, alpha- or beta-galactosidase, alpha-mannosidase, beta-N-acetylhexosaminidase, beta-glucuronidase, alpha-L-fucosidase. Fifty-percent inhibition of beta-glucosidase required about 10 micrograms/ml of castanospermine. The amount of inhibition was uniform throughout the time course, and the inhibition with regard to substrate concentration (p-nitrophenyl-beta-D-glucopyranoside) appeared to be of the mixed type. Castanospermine was also a potent inhibitor of beta-glucocerebrosidase when assayed with fibroblast extracts using either a fluorimetric or a radioactive assay. Interestingly enough, castanospermine also inhibited the lysosomal alpha-glucosidase, and this inhibition required comparable levels of alkaloid to that required for inhibition of beta-glucocerebrosidase. However, a number of other lysosomal glycosidases were not sensitive to castanospermine (i.e., alpha- or beta-galactosidase, alpha- or beta-mannosidase, alpha- or beta-L-fucosidase, beta-N-acetylhexosaminidase, beta-glucuronidase).
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PMID:Castanospermine, a tetrahydroxylated alkaloid that inhibits beta-glucosidase and beta-glucocerebrosidase. 640 22

1. Acid lysosomal and neutral alpha-glucosidase activities are measured during the culture of five human malignant epithelial cell lines, as a function of the growth-related glycogen accumulation. 2. Neutral alpha-glucosidase is found to be active mainly during the exponential phase of cell culture, which could be related to an enhancement of glycosylated compound synthesis. 3. The latent activity of the acid lysosomal alpha-glucosidase increases during the course of cell culture and especially when glycogen accumulates, suggesting that this enzyme could be involved in the control of the polysaccharide storage within the cell.
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PMID:Variations of glycogen level and alpha-glucosidase activity in human malignant epithelial cell lines in culture. 680 87

Two mutations in the lysosomal alpha-glucosidase gene, a single base pair deletion (delta T525) and a deletion of exon 18, have recently been identified with a relatively high incidence in Caucasian patients with glycogen storage disease type II (GSD II). Prenatal diagnosis was made in a pregnancy of consanguineous parents of a child with GSD II. The delta T525 deletion was demonstrated in this family but unexpectedly in only one of the parents. The absence of the delta T525 deletion in DNA isolated from the chorionic villi and a normal alpha-glucosidase activity indicated that the fetus was not affected. The possible role of mutation analysis in the prenatal diagnosis of GSD II is discussed in the light of our previous experience from a series of 100 prenatal diagnoses for this disorder by enzyme analysis.
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PMID:Prenatal diagnosis of glycogen storage disease type II: enzyme assay or mutation analysis? 747 85


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