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)

Both the common and a variant isozyme of acid alpha-glucosidase have been purified from a heterozygous placenta with CM-Sephadex, ammonium sulfate precipitation, dialysis, Amicon filtration, affinity chromatography by Sephadex G-100, and DEAE-cellulose chromatography. Three and two activity peaks, from the common and variant isozymes, respectively, were obtained by DEAE-cellulose chromatography using a linear NaCl gradient. The three peaks of activity of the common isozyme were eluted with 0.08, 0.12, and 0.17 M NaCl, whereas the two peaks of the variant, with 0.01 and 0.06 M NaCl. The pH optimum and thermal denaturation at 57 degrees C were the same in all enzyme peaks of both isozymes. Rabbit antiacid alpha-glucosidase antibodies produced against the common isozyme were found to cross-react with both peaks of the variant isozyme. The two isozymes shared antigenic identity and had similar Km's with maltose as substrate. Normal substrate saturation kinetics were observed with the common isozyme when glycogen was the substrate, but the variant produced an S-shaped saturation curve indicating a phase of negative and positive cooperativity at low and high glycogen concentrations, respectively. The activity of the variant was only 8.6% and 19.2% of the common isozyme when assayed with nonsaturating and saturating concentrations of glycogen, respectively. A similar rate of hydrolysis of isomaltose by both isozymes was found indicating that the reduced catalytic activity of the variant isozyme toward glycogen is not the result of a reduced ability of this enzyme to cleave the alpha-1,6 linkages of glycogen.
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PMID:An isozyme of acid alpha-glucosidase with reduced catalytic activity for glycogen. 677 Jun 74

The activities of various glycosidases in homogenates of the small intestinal mucosa of two adult and 18 suckling tammar wallabies (M. eugenii) aged from 6 to 50 weeks were investigated. Lactase (beta-D-galactosidase), beta-N-acetylglucosaminidase, alpha-L-fucosidase and neuraminidase activities were high during the first 34 weeks post partum and then declined to very low levels. Maltase, isomaltase, sucrase and trehalase activities were very low or absent during the first 34 weeks, and then increased. The lactase activity was unusual in being greater in the distal than the middle or proximal thirds of the intestine, and in its low pH optimum (pH 4.6), inhibition by p-chloromercuribenzene sulfonate but not by Tris, and lack of cellobiase activity. These properties are those of a lysosomal acid beta-galactosidase rather than of a brush border neutral lactase. The maltase activity had the characteristics of a lysosomal acid alpha-glucosidase early in lactation and of a brush border neutral maltase in adult animals. The significance of these findings is discussed in relation to changes in dietary carbohydrates during weaning and to the mode of digestion of milk carbohydrates by the pouch young.
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PMID:Intestinal lactase (beta-galactosidase) and other glycosidase activities in suckling and adult tammar wallabies (Macropus eugenii). 678 21

We present a case of glycogen storage disease type II (Pompe's disease) with the classical clinical presentation and characteristic electrocardiographic changes of this disorder. An acid maltase (EC 3.2.1.20) determination in the peripheral leukocytes revealed normal activity; however, acid maltase activity was completely absent in a pre-mortem skeletal muscle biopsy. Post-mortem studies showed acid maltase activity to be absent in all tissues examined, including cultured skin fibroblasts. Massive glycogen deposition corresponded to the localization of the enzymic deficiency, except in the brain, where glycogen content was within the normal range. The acid maltase activity in mixed peripheral leukocytes was due to an isoenzyme of acid maltase in the granulocyte series. Antenatal diagnosis was accurate in a subsequent pregnancy, but discordance between enzyme activity in different cell lines in an individual with a genetic disease is a conceivable source of error in both prenatal and postnatal diagnoses.
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PMID:Apparent normal leukocyte acid maltase activity in glycogen storage disease type II (Pompe's disease). 700 67

The activities of acid and neutral maltase were measured in lymphocytes, granulocytes, and platelets isolated from controls and from 5 patients with late-onset acid maltase deficiency (AMD). Lymphocytes from patients had markedly decreased activity of acid maltase and elevated neutral/acid ratios. In granulocytes, acid maltase was also lower than in controls, but significant activity was retained at pH 4: neutral/acid ratios were consistently elevated. Normal platelets had low acid and high neutral maltase activities: both enzyme activities varied within wide ranges and patients could not be distinguished from controls. The variable proportion of different cell types in unfractionated leukocyte preparations may yield unreliable values when used for detection of AMD. However, lymphocytes isolated from 20 ml of blood provide a readily accessible and reliable source of tissue for accurate diagnosis.
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PMID:Late-onset acid maltase deficiency. Biochemical studies of leukocytes. 701 86

The average activity levels of acid alpha-glucosidase are comparable in liver supernatant fluids for 15 cystic fibrosis patients and 12 controls (401 +/- 131 and 347 +/- 109 nmol/h/mg protein, respectively) and no significant differences were found for the cystic fibrosis and control liver acid alpha-glucosidases in their (a) apparent Km values for the 4-methylumbelliferyl substrate (1.1 mmol/l), (b) pH optima (4.2) and thermostability curves and (c) isoelectric profiles (one form with an isoelectric point of 4.5 +/- 0.2). In contrast, average neutral alpha-glucosidase activity levels were significantly increased (p less than 0.0002) in sera from 21 cystic fibrosis patients compared to 15 controls (10.7 and 2.7 nmol/h/ml). This increased activity is not due to (a) different stability upon storage at --20 degrees C, (b) the presence of activators in cystic fibrosis sera or inhibitors in normal sera (as determined by mixing studies), (c) altered Km values or (d) altered pH optima curves. Cystic fibrosis serum neutral alpha-glucosidase appears to be more thermostable and has a consistently altered isoelectric profile (greater percentage of activity above pI 4.8) when compared to the normal serum enzyme. This altered isoelectric composition may reflect changes in neutral alpha-glucosidase which contribute to its increased activity in cystic fibrosis sera.
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PMID:Activity levels and properties of acid alpha-glucosidase from liver and neutral alpha-glucosidase from sera of cystic fibrosis patients and controls. 703 May 25

Amniotic fluid in midpregnancy contains significant alpha-glucosidase activity. This enzyme is distinguishable from the lysosomal acid alpha-glucosidase, deficiency of which is associated with Pompe's disease. The two enzymes differ in optimum pH, thermal stability, electrophoretic migration, isoelectric point, molecular mass, and immunological response. Amniotic alpha-glucosidase is also different from the classical neutral form. Immuno-cross reactions suggest that the amniotic fluid enzyme has a double fetal origin: renal and intestinal. It seems that alpha-glucosidase in amniotic fluid is linked to lipids.
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PMID:Human amniotic fluid alpha-glucosidase. 703 30

Acid alpha-glucosidase (E.C. 3.2.1.3) was purified more than 60,000-fold from rat liver. Antibody was obtained by injection of this pure enzyme into rabbits with Freund's complete adjuvant. The resultant anti-acid alpha-glucosidase immunoglobulin (Ig) G was digested with pepsin and then F(ab')2 was treated with 2-mercaptoethanol. Coupling of Fab' to horseradish peroxidase was performed according to the method of Wilson and Nakane. Light microscopic observation of the immunohistochemical localization of this enzyme in rat hepatocytes revealed small granular deposits of diaminobenzidine reaction products. The reaction diffusely observed in the hepatocyte cytoplasm of any area. Under the electron microscope, the reaction precipitates were found to be located on the lysosome membrane, particularly on the inner side of the membrane, as small dots. The small vesicles were strongly positive for this reaction. Occasionally positive reaction were also demonstrated in the lumen of the secondary lysosomes. However, the Golgi and its associated structures did not show a positive reaction.
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PMID:Immunohistochemical localization of acid alpha-glucosidase in rat liver. 703 44

A biochemical study was performed in a Lapland dog suspected of glycogen storage disease type II (acid alpha-glucosidase deficiency, Pompe's disease). Glycogen content was substantially elevated in heart and skeletal muscle but not in the liver. Severely reduced activities of acid alpha-glucosidase (EC 3.2.1.20) were found in heart, skeletal muscle, liver and cultured tongue fibroblasts. The deficiency was located in the glycoprotein fraction, which supported its lysosomal origin. The electrophorogram showed after acid incubation that the affected dog was missing the activity band, while after neutral incubation the pattern was similar to control. The obtained biochemical data are compared with the known data of the human pathology.
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PMID:Canine glycogen storage disease type II. A biochemical study of an acid alpha-glucosidase-deficient Lapland dog. 704 88

Treatment with sodium metaperiodate caused oxidation of carbohydrate residues in acid alpha-glucosidase (gamma-amylase). Efficiency of the oxidation was monitored by a decrease in specific binding of alpha-glucosidase with concanavaline A-Sepharose. The degree of oxidation reached 96% in a medium containing 0,011 M NaIO4, pH 5.5, within 120 min. The residual activity of oxidized alpha-glucosidase was about 77%. The rate of oxidation and residual enzymatic activity were shown to depend also on concentration of sodium metaperiodate and duration of the reaction.
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PMID:[Effect of periodate oxidation on activity of acid alpha-glucosidase from human liver]. 704 34

Chemical modification of the COOH-groups of acid alpha-glucosidase from human liver by 1-ethyl-3 (3'-dimethylaminopropyl) carbodiimide. HCl in the presence of rho-aminophenyl-beta-D-galactopyranoside was carried out. The presence of covalently bound galactose derivative in the enzyme was followed by changes in the absorption spectra and electrophoretic mobility during polyacrylamide gel electrophoresis and by the ability of modified alpha-glucosidase to interact specifically with castor-bean lectin (RCA II). The modified enzyme retained its catalytic activity towards maltose and did not differ from native alpha-glucosidase in terms of its affinity for this substrate, the Km values for maltose during 5 and 6 mM, respectively. The in vitro changes in the marker specificity of acid alpha-glucosidase against the unchanged catalytic properties of the enzyme are discussed.
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PMID:[Chemical attachment of p-aminophenylgalactoside to acid alpha-glucosidase from human liver]. 705 47


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