Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acid alpha-glucosidase (EC 3.2.1.20) was purified from human placenta and bovine testis by affinity chromatography using concanavalin A (conA) and Sephadex G 200. When added to the culture medium of human fibroblasts, the enzyme purified from bovine testis is taken up with a 200-fold higher efficiency than the enzyme from human placenta. Uptake of acid alpha-glucosidase from bovine testis is mediated by the mannose-6-phosphate receptor, whereas only a minor fraction of placental enzyme appears to be equipped with the mannose-6-phosphate recognition marker. Once internalized, both human and bovine acid alpha-glucosidase demonstrate a half-life of about 10 days in fibroblasts from control individuals and patients with different clinical forms of glycogenosis type II (Pompe's disease, acid alpha-glucosidase deficiency). Evidence is presented that the mannose-6-phosphate receptor is also present on the plasma membrane of the clonal myogenic skeletal muscle cell lines G8-1 and L6J1 (respectively from mouse and rat origin) and on cultured human skeletal muscle cells derived from a muscle biopsy. Addition of bovine testis acid alpha-glucosidase to skeletal muscle cell cultures from an adult patient with glycogenosis type II leads to complete correction of the enzyme deficiency.
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PMID:Uptake and stability of human and bovine acid alpha-glucosidase in cultured fibroblasts and skeletal muscle cells from glycogenosis type II patients. 623 28

The developmental patterns of four lysosomal enzymes have been investigated in liver, kidney, lung, heart, spleen, muscle and brain tissues of human fetuses at varius gestational ages. The largest increment in the activity of all four enzymes, namely acid alpha-glucosidase, alpha-galactosidase, beta-galactosidase and acid phosphatase had been observed in kidney with a 6- to 12-fold increase between the second and third trimester of gestation. The activity of all liver and spleen enzymes also increased considerably during these periods. In muscle, however, only alpha-glucosidase and acid phosphatase showed an increase in the activity, and in lung, acid phosphatase and beta-galactosidase. Most of brain and heart enzymes, except acid phosphatase, did not change significantly during the observation period. The activities of these lysosomal enzymes were also measured in tissues of a normal adult individual, and aspects of the neonatal and postnatal development of these enzymes were discussed.
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PMID:Lysosomal enzyme activities of human fetal organs during development. 625 27

Glycogen storage diseases of type I, II, III, IV, V and the other muscle types, were examined electron microscopically, biochemically and physicochemically. Glycogenosomes (glycogen containing vacuoles) were found in the affected tissues of type II, type III variant of muscle glycogen storage disease, type IV and muscle type phosphorylase b kinase deficiency (disorder of the phosphorylase b kinase activation mechanism). The acid alpha-glucosidase activity was decreased only in the case of type II glycogen storage disease (Pompe's disease). The other types of glycogen storage disease showed no decrease in acid alpha-glucosidase activity. Moreover, one patient with type II disease also revealed a decrease in neutral alpha-glucosidase activity. In all cases where glycogenosomes were found, the extracted glycogen macromolecules showed some molecular abnormality or deviation when compared with normal native glycogen macromolecules.
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PMID:Glycogen storage disease. Studies related to the mechanism of glycogenosome formation. 630 67

The use of a synthetic substrate (p-nitrophenyl-alpha-D-glucoside) to measure alpha-glucosidase activity has allowed us to demonstrate the presence of acid and neutral alpha-glucosidases in the reproductive organs of the male rat. Both enzymes increased in the epididymis, particularly in the caput segment, along with initiation of spermatogenesis at puberty; it then started decreasing after 12 weeks of life. Similar variations were not recorded in testis, prostate, and seminal vesicles. Castration led to a significant decrease of acid and neutral alpha-glucosidases in all accessory reproductive organs, but administration of testosterone proprionate (50 micrograms/day for 10 days) restored the enzyme activity to its original level. When estradiol-17 beta (5 mg) was administered simultaneously with testosterone (500 micrograms), the antagonistic effect of estradiol on testosterone was particularly evident on the levels of neutral alpha-glucosidases which reached the castration range, while the acid alpha-glucosidase remained unchanged in epididymis, prostate, and seminal vesicles. These results show that both acid and neutral alpha-glucosidases may be influenced by gonadal hormones in the male rat.
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PMID:Presence of alpha-glucosidases in the male reproductive system of the rat and hormonal influences. 635 99

Most biological fluids contain both neutral and acid alpha-glucosidase. Optimal conditions were therefore developed for the selective determination of the activity of neutral and acid alpha-glucosidase, using 2-step, discontinuous assays. In the first step of the assay of neutral alpha-glucosidase, glucose was liberated from maltose (citrate-phosphate buffer, pH 6.8, 20 mmol/l maltose, 25 mmol/l turanose). Under these incubation conditions, turanose inhibited the residual activity of acid alpha-glucosidase almost completely without influencing the activity of neutral alpha-glucosidase. In the first step of the acid alpha-glucosidase assay, glucose was liberated from maltose (citrate-phosphate buffer, pH 3.8, 50 mmol/l maltose, 2 mol/l potassium chloride). Under these incubation conditions, potassium ions stimulate the activity of acid alpha-glucosidase and simultaneously inhibit almost completely the residual activity of neutral alpha-glucosidase. In the second step of the assay of neutral and acid alpha-glucosidase, the liberated glucose was measured by hexokinase/glucose-6-phosphate dehydrogenase. The effect of turanose and potassium ions on neutral and acid alpha-glucosidase from human urine was characterized.
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PMID:Selective determination of the activities of neutral and acid alpha-glucosidase using discontinuous assays. 635 65

The catalytic activities of neutral and acid alpha-glucosidase were selectively determined in human urine. Urinary excretion of neutral and acid alpha-glucosidase in reference subjects was found to be in the range 1.61 to 20.36 microkat/mol creatinine and 7.47 to 33.60 microkat/mol creatinine, respectively. Urinary excretion of both enzymes was not related to sex, age or diuresis. A continuous assay was introduced to improve the determination of neutral alpha-glucosidase.
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PMID:Excretion of neutral alpha-glucosidase, determined with a continuous assay, and of acid alpha-glucosidase in the urine of human reference subjects. 635 66

In the kidneys of two infants who died from glycogenosis type II (deficiency of lysosomal acid alpha-glucosidase) the activity of alpha-glucosidase at acid pH was absent only from the medulla but not the cortex. This prompted an investigation of acid and neutral alpha-glucosidases of the two zones of normal human kidney and of liver. In the kidney medulla, a single, fast migrating electrophoretic band was active at neutral but not at acid pH. In the cortex, three additional bands were detected at neutral pH and two in the liver. One slowly migrating band was unique to the cortex and active over a broad pH range. It had comparatively high sensitivity to the inhibitor turanose and high heat stability. Its properties suggested a close relationship or identity to glucoamylase of the intestinal brush border membrane and to alpha-glucosidase in leukocytes and amniotic fluid and cells.
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PMID:Zonal differences of alpha-glucosidases in human kidney: studies in controls and in patients with glycogenosis type II. 635 53

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

Messenger RNA was isolated from monkey testes and size-fractionated on sucrose gradients. In vitro translation of these mRNA fractions resulted in nascent, labeled alpha-glucosidase that could be precipitated with anti human alpha-glucosidase antiserum. A cDNA library was constructed from the most enriched fraction. The library was screened with cDNA made from mRNA obtained from immunoselected polysomes. Five cross-hybridizing clones were isolated and identified by their selection of alpha-glucosidase mRNA, as shown by hybrid released translation and further by their ability to hybridize with DNA from human chromosome 17, on which the gene coding for acid alpha-glucosidase is located.
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PMID:Cloning a cDNA for the lysosomal alpha-glucosidase. 636 44

Activities of acid and neutral alpha-glucosidases (EC 3.2.1.3 and EC 3.2.1.20, respectively) were compared in human lymphocytes and granulocytes. As shown by means of antibodies to acid alpha-glucosidase, this enzyme prevailed in lymphocytes while in granulocytes it constituted only a slight part of the total alpha-glucosidase activity. Neutral alpha-glucosidases of both these cells were distinctly dissimilar. Neutral alpha-glucosidase from granulocytes exhibited more wide pH optimum as compared with the lymphocyte enzyme, at the same time, the granulocyte enzyme was stable at pH 4.0, 37 degrees, 15 min and was inhibited by turanose. The data obtained suggest that granulocyte neutral alpha-glucosidase was similar to the same enzyme from kidney, whereas lymphocyte neutral alpha-glucosidase--to the enzyme from liver tissue.
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PMID:[Comparative study of the alpha-glucosidase activity of lymphocytes and granulocytes of human peripheral blood]. 636 75


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