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 maltase deficiency in adults is associated with progressive muscle weakness and may effect respiratory muscles resulting in respiratory failure. The biochemical and clinical manifestations of acid maltase deficiency arise from a marked deficiency of the lysosomal enzyme alpha-glucosidase (acid maltase), which normally degrades glycogen to free glucose. In the past few years, high-protein diets have provided an alternative energy source for these patients and resulted in improved muscle strength. Recently, we treated a ventilator-dependent acid maltase-deficient patient with a general diet supplemented with branched-chain amino acids. Branched-chain amino acids are the principal amino acids involved in muscle protein synthesis and utilization. While on this diet, the patient had improvement of respiratory function and muscle strength and was able to be weaned from the ventilator during the day. In addition to his nutritional status, levels of serum branched-chain amino acids, showed improvement within 2 months after the diet started. This diet shows potential advantages over a high-protein diet without supplemented branched-chain amino acids for the treatment of acid maltase deficiency. These include theoretical sparing of amino acids required for muscle protein synthesis by providing higher concentrations of postprandial branched-chain amino acids in the circulation. Also, the liquid formula would be better tolerated by a ventilator-dependent or debilitated patient rather than a high-protein general diet. Further experience with branched-chain amino acid formulas will be needed to substantiate their efficacy in the treatment of acid maltase deficiency.
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PMID:Treatment of acid maltase deficiency with a diet high in branched-chain amino acids. 211 30

We describe the partial characterization and some properties of leucocyte alpha-glucosidase towards disaccharides with the alpha-1,4 (maltose) and alpha-1,6-glucosidic linkage (isomaltose) and tetrasaccharides with the alpha-1,4 (maltotetraose) and alpha-1,6-glucosidic linkage (tetrasaccharide, Glc alpha 1----6Glc alpha 1----4Glc alpha 1----4Glc, which was isolated from the urine of a patient with glycogenosis type II). Leucocyte alpha-glucosidase showed optimal activity towards all four oligosaccharides under two conditions, acidic (pH 4.0-4.5) and neutral (pH 6.0-6.5) regions. Our comparative studies on enzyme kinetics showed that leucocyte alpha-glucosidase was able to hydrolyze both the 1----4 isomers and the 1---6 isomers at acidic and neutral pH. Acid alpha-glucosidase could hydrolyze maltose about 10 times faster than isomaltose, and maltotetraose about 5 times faster than tetrasaccharide isolated from urine. In leucocytes of the patient with late onset glycogenosis type II, acid alpha-glucosidase activities towards maltose, isomaltose, maltotetraose and tetrasaccharide isolated from urine showed 75.3%, 67.4%, 76.5% and 41.4% of normal control values, respectively. Neutral alpha-glucosidase activities towards these four oligosaccharides were normal. Tetrasaccharide with alpha-1,6-glucosidic linkage might be accumulated by the impaired hydrolysis in the circulation as well as the leakage of undegraded glycogen to the circulation from the affected muscle.
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PMID:Leucocyte alpha-1,4- and alpha-1,6-glucosidase activities towards oligosaccharides in late onset glycogenosis type II. 225 8

We describe the biochemical characterization of lymphocyte alpha-glucosidase in a 23-year-old man with intermediate clinical features between the childhood and adult forms of glycogenosis type II (Pompe's disease). Acid alpha-glucosidase activity was markedly reduced, but immunologic cross-reactive material against human liver acid alpha-glucosidase protein could be detected, and its amount was normal. In this patient, the disorder was induced by the catalytically inactive enzyme with a normal amount of enzyme protein.
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PMID:Lymphocyte alpha-glucosidase in late-onset glycogenosis type II. 246 29

The effect of the glucose analogue N-hydroxyethyl-1-deoxynojirimycin (BAY m 1099) on the activity of alpha-glucosidases was studied in human fibroblasts and HepG2 cells. BAY m 1099 inhibits neutral and acid alpha-glucosidase activities of both cell types in a dosage-dependent and reversible manner. Inhibition of endoplasmic reticulum glucosidases I and/or II is suggested by delayed processing of lysosomal (acid) alpha-glucosidase. Competitive inhibition of mature acid alpha-glucosidase leads to lysosomal accumulation of glycogen as in glycogenosis type II. There seems to be little risk, however, of inducing this storage disorder when using the drug in a dose of 50 mg per os for treatment of type II diabetes. In high doses, the drug may prove useful for studying the pathogenesis of glycogenosis type II in vitro or in animal models.
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PMID:Effects of N-hydroxyethyl-1-deoxynojirimycin (BAY m 1099) on the activity of neutral- and acid alpha-glucosidases in human fibroblasts and HepG2 cells. 254

Pompe's disease is characterised by an absence of lysosomal alpha-glucosidase, but this enzyme is also inhibited by Castanospermum australe seeds. Four calves were fed C. australe seeds at the rate of 0.15 g/kg body weight for periods from 1 to 4 days. Lymphocyte alpha-glucosidase activity was reduced by at least 90%, with the majority of inhibition occurring within 8 h of dosing. Several weeks elapsed before activity returned to normal. Significant inhibition of muscle alpha-glucosidase occurred and the ratio of plasma alpha-glucosidase activity measured at pH 5.6 relative to that at pH 3.7 was depressed. In an attempt to induce Pompe's disease, 2 calves were dosed with 1.2 g C. australe seed/kg body weight/day for 13 months. Lymphocyte and muscle alpha-glucosidase activities were markedly reduced over the entire period of feeding, but the animals showed no clinical signs of disease. Tissue cells were not vacuolated nor did they show any apparent accumulation of glycogen. Despite significant inhibition of alpha-glucosidase in skeletal and cardiac muscle, liver, kidney and brain, it is suggested that there was sufficient residual enzyme to prevent induction of a phenocopy of Pompe's disease.
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PMID:Inhibition of alpha-glucosidase in cattle by Castanospermum australe: an attempted phenocopy of Pompe's disease. 265 94

We describe partial characterization and properties of leucocyte alpha-glucosidase from a patient with clinical features intermediate of juvenile and adult onset forms of glycogenosis type II. Acid and neutral alpha-glucosidase activities toward 4-methylumbelliferyl glucopyranoside as substrate were studied in total leucocytes, and separately in lymphocytes and granulocytes. Lymphocytes, which showed markedly reduced activities of acid alpha-glucosidase in the patient, are the most reliable peripheral blood cells for the diagnosis of glycogenosis type II. Moreover, the ratio of acid/neutral alpha-glucosidase activities, especially in lymphocytes, is a useful parameter for the diagnosis. In lymphocytes, the Km values of both acid and neutral alpha-glucosidases were essentially the same between the patient and normal controls; the Vmax value of acid alpha-glucosidase from the patient was markedly reduced, and the Vmax value of neutral alpha-glucosidase from the patient was reduced by 36% as compared with that from normal controls. Heat-inactivation experiments revealed that acid alpha-glucosidase activities of lymphocytes were relatively heat-stable, while both acid and neutral alpha-glucosidases of granulocytes were heat-labile. No differences in these properties, however, could be detected between the patient and normal controls.
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PMID:Partial characterization of leucocyte alpha-glucosidase in late onset glycogenosis type II. 266 74

The lysosomal storage disorder glycogenosis type II, caused by a deficiency of lysosomal alpha-glucosidase, is very heterogeneous in its clinical presentation. It has been suggested that this heterogeneity may be due to differential expression of neutral alpha-glucosidases. We have therefore analysed the activity of the major neutral alpha-glucosidases in cultured fibroblasts or muscle cells from 26 patients with glycogenosis type II. The results indicate that there is no correlation between the expression of neutral alpha-glucosidase isoenzymes and the clinical phenotype of this disease.
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PMID:An investigation of the possible influence of neutral alpha-glucosidases on the clinical heterogeneity of glycogenosis type II. 268 40

In Japanese quails with late-onset acid maltase deficiency (AMD), the activity of acid alpha-glucosidase was severely reduced to approximately 16% of the normal level from an embryonic age. The kinetic characteristics and inhibition by Zn indicated that the residual activity was responsible for the intrinsic activity of acid alpha-glucosidase. However, in affected embryos, the glycogen content and other lysosomal enzyme activities were normal, despite the low acid alpha-glucosidase activity. In a separate study, we found the existence of two age-dependent neutral alpha-glucosidases--"embryonic" and "adult" alpha-glucosidases. In affected quails, the transition from the embryonic neutral alpha-glucosidase to the adult type was not influenced by the disease. The activity toward maltose and glycogen of the embryonic neutral alpha-glucosidase may explain the normal glycogen content in the affected embryos.
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PMID:Developmental study of alpha-glucosidases in Japanese quails with acid maltase deficiency. 309 Apr 32

Prenatal diagnosis of glycogenosis type II was performed by direct assay of acid alpha-glucosidase (EC 3.2.1.20) in chorionic villous biopsy obtained by transcervical cannula aspiration from a pregnancy at risk in the 10th week of gestation. The exact value of the enzyme activity estimated by the use of antibody preparations for purified human liver acid alpha-glucosidase was in the heterozygous range, and so the homozygous enzyme deficiency could be excluded. The subsequent analysis of cells cultured from amniocentesis sampling in the 18th week of gestation resulted in a similar outcome. The study with antibodies showed that in 23 control chorionic villi obtained during gestational ages between 7-13 weeks, 1-15% of the total alpha-glucosidase activity at pH 4.0 were due to renal or neutral enzyme. This indicates that it may be important to employ antibodies for prenatal diagnosis using chorionic villous sampling. A healthy and unaffected boy was born. The biochemical values obtained from an umbilical blood specimen were in accordance with the results of the prenatal diagnosis.
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PMID:First trimester diagnosis of Pompe's disease (glycogenosis type II) with normal outcome: assay of acid alpha-glucosidase in chorionic villous biopsy using antibodies. 309 66

We measured the activities of two major forms of alpha-glucosidase in lymphocytes and cultured fibroblasts from normal healthy controls and patients with Pompe's disease by using 4-methylumbelliferyl-alpha-D-glucoside as substrate. We found (1) enzyme activity of the pH 4 and pH 6 forms varied with age, and (2) patients with Pompe's disease showed very low activity of the pH 4 form and a low ratio of pH 4 to pH 6 forms. We established a reference range and were also able to diagnose prenatally the homozygote and heterozygote forms of Pompe's disease which occurred in families of southern Chinese and aborigines in Taiwan. This enzyme biochemical study may be useful in anthropology.
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PMID:Pompe's disease in Chinese and prenatal diagnosis by determination of alpha-glucosidase activity. 310 10


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