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)

The effect of supplementation of the diet with galactose on the age-related decline of intestinal lactase activity was investigated in 108 growing rats. Starting from 14 days of age, the rats were divided into two groups and fed with chow, and with fluid either as tap water or 5% galactose solution. At 14 days the specific lactase activity was 112.8 +/- 3.2 mumol min-1 (g protein)-1, which decreased to less than 10% of this value at maturity. Galactose supplementation did not prevent the decline. The increase of maltase, sucrase and trehalase was also unaffected. The result suggests that galactose plays no significant role in the regulation of disaccharidase activities in the rat.
Exp Physiol 1990 Sep
PMID:The effect on intestinal disaccharidase activity of feeding galactose to growing rats. 224 21

Previous work from our laboratory has shown that the intestine of the suckling rat, unlike adult rat intestine, contains abundant quantities of at least two soluble neutral maltase-glucoamylases. These enzymes are related antigenically to membrane-bound maltase-glucoamylase, which predominates in adult intestine, but are either more easily solubilized or occupy a different cellular locus. To study the soluble enzymes further, we attempted their isolation from the intestine of 11-day-old suckling rats. Initial attempts were complicated by proteolytic degradation, despite the addition of phenylmethylsulfonyl fluoride, N-ethylmaleimide, leupeptin, pepstatin, and EDTA to buffers used for homogenization and column chromatography. Addition of aprotinin, amastatin, bestatin, and phosphoramidone resulted, however, in the isolation of two stable, high molecular weight maltases (HM1 and HM2). Both enzymes eluted before a papain-solubilized membrane-derived maltase-glucoamylase on Sepharose 4B and were separable by DE-52 and Sepharose 6B - Tris affinity columns. They were further purified on a lentil lectin - Sepharose 4B column. Substrate specificities were almost the same and characteristic of maltase-glucoamylases. Hydrophobic binding properties and pH optima of HM1 and HM2 were also similar. HM1 was resolved by sodium dodecyl sulfate - polyacrylamide gel electrophoresis into approximately equal portions of an endo-beta-N-acetylglucosaminidase H sensitive enzyme of molecular weight (MW) 200,000 and an endo-beta-N-acetylglucosaminidase H resistant but endo-beta-acetylglucosaminidase F sensitive enzyme of MW 400,000. In contrast, most of HM2 consisted of a doublet of MW 200,000 - 210,000 that was endo-beta-N-acetylglucosaminidase H sensitive. The intestine of the suckling rat, therefore, contains two soluble maltase-glucoamylase fractions, with a major portion of high mannose rather than complex oligosaccharides.(ABSTRACT TRUNCATED AT 250 WORDS)
Biochem Cell Biol 1990 Sep
PMID:High molecular weight soluble neutral maltase-glucoamylases in the intestine of the suckling rat. 225 17

Neutral alpha-D-glucosidase (alpha-D-glucoside glucohydrolase, EC 3.2.1.20) from horse kidney brush-border membranes was solubilized using Emulphogene BC 720 and purified by an affinity chromatography technique. The enzyme preparation (390-fold purified), which was free of other known microvillus hydrolases, exhibited one precipitate line in crossed immunoelectrophoresis and migrated as a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Several criteria (charge-shift crossed immunoelectrophoresis and hydrophobic chromatography) revealed the purified detergent form of the enzyme to be an amphipathic molecule. The papain treatment of either brush-border membrane vesicles or the purified detergent form of neutral alpha-D-glucosidase released an enzymatic form devoid of these amphipathic properties. Conversely, after trypsin treatment of the "d' form of the enzyme, two enzymatic forms were obtained: the first and major form retained these amphipathic properties; the second form exhibiting the same properties as the papain-released form. Furthermore, only a very small amount of neutral alpha-D-glucosidase can be released after trypsin solubilization of brush-border membrane vesicles, and the released enzyme did not exhibit amphipathic properties. These results were interpreted as meaning that the trypsin attack site on the detergent form of the enzyme had either poor affinity for, or obstructed access to, the proteinase when the enzyme was integrated in native membrane or in Triton X-100 micelles, whereas the proteolytic site of the papain was always accessible.
Biochim Biophys Acta 1985 Sep 20
PMID:Horse kidney neutral alpha-D-glucosidase: purification of the detergent-solubilized enzyme; comparison with the proteinase-solubilized forms. 241 88

The endoplasmic reticulum-localized enzyme alpha-glucosidase II is responsible for removing the two alpha-1,3-linked glucose residues from N-linked oligosaccharides of glycoproteins. This activity is missing in the modA mutant strain, M31, of Dictyostelium discoideum. Results from both radiolabeled pulse-chase and subcellular fractionation experiments indicate that this deficiency did not prevent intracellular transport and proteolytic processing of the lysosomal enzymes, alpha-mannosidase and beta-glucosidase. However, the rate at which the glucosylated precursors left the rough endoplasmic reticulum was several-fold slower than the rate at which the wild-type precursors left this compartment. Retention of glucose residues did not disrupt the binding of the precursor forms of the enzymes with intracellular membranes, indicating that the delay in movement of proteins from the ER did not result from lack of association with membranes. However, the mutant alpha-mannosidase precursor contained more trypsin-sensitive sites than did the wild-type precursor, suggesting that improper folding of precursor molecules might account for the slow rate of transport to the Golgi complex. Percoll density gradient fractionation of extracts prepared from M31 cells indicated that the proteolytically processed mature forms of alpha-mannosidase and beta-glucosidase were localized to lysosomes. Finally, the mutation in M31 may have other, more dramatic, effects on the lysosomal system since two enzymes, N-acetylglucosaminidase and acid phosphatase, were secreted much less efficiently from lysosomal compartments by the mutant strain.
Arch Biochem Biophys 1989 Sep
PMID:Biogenesis of lysosomal enzymes in the alpha-glucosidase II-deficient modA mutant of Dictyostelium discoideum: retention of alpha-1,3-linked glucose on N-linked oligosaccharides delays intracellular transport but does not alter sorting of alpha-mannosidase or beta-glucosidase. 250 71

Miglitol (BAYm 1099), an alpha-glucosidase inhibitor, reduces the postprandial increase of blood glucose and serum insulin levels in type II (non-insulin-dependent) diabetes mellitus, as shown in short-term studies. In this study, the effects of long-term miglitol treatment on metabolic control, C-peptide secretion, hepatic glucose output, and peripheral insulin sensitivity (euglycemic clamp) were tested in 15 type II diabetic patients (8 receiving insulin, 7 receiving oral hypoglycemic agents). For 8 wk they received either miglitol (300 mg/day) or placebo with a double-blind crossover design that had a 4-wk washout period between treatments. Miglitol therapy induced a reduction of postprandial blood glucose levels (miglitol compared with placebo; areas under the curve; P less than .002), whereas fasting blood glucose levels were not influenced. Miglitol caused a slight reduction of glycosylated hemoglobin levels (mean +/- SE miglitol and placebo 9.50 +/- 0.3 and 10.0 +/- 0.4%, respectively; P less than .05), which was more pronounced in insulin-treated patients. Miglitol caused a reduction of postprandial C-peptide increase (P less than .03). Hepatic glucose output (both in the basal state and during euglycemic clamp conditions) and peripheral insulin sensitivity were not influenced by miglitol therapy. Specific side effects were observed in 11 patients; in 6 patients only to a moderate degree. Long-term miglitol treatment induces a persistent reduction of postprandial blood glucose increase. This effect is more pronounced in type II diabetic patients on insulin therapy, which can cause a moderate improvement of overall metabolic control.
Diabetes Care 1989 Sep
PMID:Effects of 8-wk alpha-glucosidase inhibition on metabolic control, C-peptide secretion, hepatic glucose output, and peripheral insulin sensitivity in poorly controlled type II diabetic patients. 267 93

The activities of lysosomal maltase in the serum, bile and liver were determined in intrahepatic cholestasis rats induced by alpha-naphtylisothiocyanate (ANIT, 200 mg/kg, i.p.), and compared with changes in alkaline phosphatase (ALP) activity. Moreover, the influences of endogenous bile acids on the release of maltase activity from the liver in intrahepatic cholestasis rats were studied. The maltase activities in the serum and bile significantly increased from 4 and 8 h after the intraperitoneal administration of ANIT, respectively. Conversely, a significant decrease in liver maltase activity was observed from 4 h after the injection of ANIT. On the other hand, total bile acid concentrations in the serum and bile significantly increased immediately after the treatment of ANIT, when biliary bile acid, exogenous bile acid or Triton X-100 was added to lysosomal fraction in the liver, the maltase activity in the supernate after the reaction significantly increased in proportion to the concentration of each substance added to the liver lysosome. These results suggested that maltase might be released from liver lysosomal membrane by surface active-action of bile acid accumulated in the liver after the administration of ANIT. Moreover, the changes in ALP activities in the serum, bile and liver after the administration of ANIT were almost similar to those in maltase activity.
Yakugaku Zasshi 1989 Sep
PMID:[The influences of endogenous bile acids on maltase and alkaline phosphatase activities in intrahepatic cholestasis rats]. 269 43

Chronic hypercapnia is associated with increased proximal HCO3 reabsorption that is thought to be mediated by a Na-H antiporter. We hypothesized that chronic hypercapnia would be associated either with increased Vmax or with decreased Km of the Na-H antiporter. To test this hypothesis we made rabbits hypercapnic for 48 h by exposure to 10% CO2. In both control and hypercapnic animals, cortical luminal membranes were enriched over the homogenate 16-fold in alkaline phosphatase and 10-fold in maltase activity. The kinetic activity of the Na-H antiporter was measured by the dissipation of the quenching of acridine orange by addition of different Na concentrations. Chronic hypercapnic rabbits had significantly higher Vmax of the Na-H antiporter of luminal membranes than controls (593 +/- 81 vs. 252 +/- 40 arbitrary fluorescence units X min-1 X 300 micrograms protein-1, P less than 0.01). The Km, however, was not different between control and hypercapnic rabbits. 22Na uptake in presence of an outwardly directed pH gradient was significantly higher in vesicles from hypercapnic rabbits than controls. Amiloride inhibited the Na-H antiporter (as assessed by acridine orange quenching or 22Na uptake) to the same degree in membranes from both control and hypercapnic rabbits, suggesting that the increase in Vmax is mediated by the electroneutral component of the Na-H antiporter. In addition, under voltage clamp conditions by K and valinomycin the Vmax was still increased in membranes from hypercapnic animals, again suggesting that the increase in Vmax is mediated by the electroneutral component of the Na-H antiporter. The uptake of D-[3H]glucose by luminal membranes was not different between control and hypercapnic rabbits, indicating a specific enhancement of the Na-H antiporter. Acute hypercapnia (4 h) failed to increase the Vmax of the Na-H antiporter despite comparable increase in PCO2. Thus chronic hypercapnia, but not acute hypercapnia, induces a selective and specific increase in the Vmax of Na-H antiporter, and this may mediate the adaptation to chronic hypercapnia.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Physiol 1987 Sep
PMID:Chronic hypercapnia enhances Vmax of Na-H antiporter of renal brush-border membranes. 282 Feb 41

In order for a yeast strain to ferment maltose it must contain any one of the five dominant MAL loci. Each dominant MAL locus thus far analyzed contains three genes: GENE 1, encoding maltose permease, GENE 2 encoding maltase and GENE 3 encoding a positive trans-acting regulatory protein. In addition to these dominant MAL loci, several naturally occurring, partially functional alleles of MAL1 and MAL3 have been identified. Here, we present genetic and molecular analysis of the three partially functional alleles of MAL1: the MAL1p allele which can express only the MAL activator; the MAL1 g allele which can express both a maltose permease and maltase; and the mal1(0) allele which can express only maltase. Based on our results, we propose that the MAL1p, MAL1g and mal1(0) alleles evolved from the dominant MAL1 locus by a series of rearrangements and/or deletions of this yeast telomere-associated locus as well as by other mutagenic processes of gene inactivation. One surprising finding is that the MAL1g-encoded maltose permease exhibits little sequence homology to the MAL1-encoded maltose permease though they appear to be functionally homologous.
Genetics 1988 Sep
PMID:The naturally occurring alleles of MAL1 in Saccharomyces species evolved by various mutagenic processes including chromosomal rearrangement. 285 83

Activities of enzyme markers of subcellular organelles have been measured in brain tissue from subjects with Alzheimer-type dementia (ATD) and Huntington's disease (HD). Significant increases in the activity of the lysosomal enzyme beta-glucuronidase were observed in both ATD temporal cortex and HD putamen. It is suggested that beta-glucuronidase activity may be a useful biochemical indicator of cellular damage in the CNS. A significant reduction in neutral alpha-glucosidase activity was observed in ATD temporal cortex and HD putamen. This change may reflect an alteration in glycoconjugate processing and may relate to the susceptibility of neurones to the degenerative processes of ATD and HD.
J Neurochem 1986 Sep
PMID:Subcellular pathology of human neurodegenerative disorders: Alzheimer-type dementia and Huntington's disease. 294 42

Castanospermine (Cas), an inhibitor of alpha-glucosidase I, blocks "trimming" of the N-linked oligosaccharide Glc3Man9GlcNAc2, thus preventing normal glycoprotein maturation. With use of a dual-label protocol, Xenopus retinas incubated in the presence of Cas exhibited at least a 2.3-fold increase in the incorporation of [3H]mannose into total retina Cl3CCOOH-precipitable material, whereas incorporation of [14C]leucine was not significantly affected, relative to controls. Analysis of NaDodSO4/PAGE fluorograms of solubilized retinas and rod outer segment (ROS) membranes indicated a relatively selective effect of Cas on opsin (the rod visual pigment apoglycoprotein). The apparent molecular mass of opsin was increased by approximately 2500 in the presence of Cas; the incorporation of [3H]mannose into opsin was enhanced about 2.3-fold without a significant effect on [14C]leucine incorporation, relative to controls. Electron microscopic autoradiography of retinas incubated for 4 hr with [3H]mannose showed that the number of newly formed ROS discs in Cas-treated retinas was not significantly different from controls, but the silver grain density over those discs was about 2.6-fold greater than in controls. The morphology of the newly formed discs was comparable under both conditions. Thus, opsin bearing abnormally large oligosaccharides can be accommodated in the process of disc morphogenesis. These results suggest that the structural requirements for opsin's oligosaccharides, with regard to their potential role as determinants of disc morphogenesis, are not stringent. Furthermore, post-translational processing of N-linked oligosaccharides is not essential for the normal intracellular routing and cell surface expression of membrane glycoproteins.
Proc Natl Acad Sci U S A 1986 Sep
PMID:Inhibition of oligosaccharide processing and membrane morphogenesis in retinal rod photoreceptor cells. 294 9


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