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)

Interactions of lipids and proteins in isolated rat intestinal microvillus membranes were examined by studying the temperature dependence of enzyme activities and of D-glucose transport in relation to the membrane lipid thermotropic transition observed by fluorescence polarization (26 +/- 2 degrees C) and differential scanning calorimetry (23--39 degrees C). Two groups of activities were defined. Enzymes of the first group, comprising lactase, maltase, sucrase, leucine aminopeptidase, and gamma-glutamyl transpeptidase, all yielded a single slope on the Arrhenius plot in the range 10--40 degrees C and did not appear to experience functionally the effects of the lipid thermotropic transition. Each activity of the second group, comprising calcium- and magnesium-dependent adenosine triphosphatases, p-nitrophenylphosphatase, and D-glucose transport, showed a change in the slope of the Arrhenius plot in the range 25--30 degrees C, corresponding to the lower region of the lipid transition. The terms "extrinsic" and "intrinsic" activities could be applied to these groups. Delipidation of the particulate p-nitrophenylphosphatase removed the discontinuity in the Arrhenius plot. Subsequent relipidation with a variety of lipids restored a break point, but the temperature corresponded to the original discontinuity (25--29 degrees C) rather than to the phase transition temperature of the exogenous lipid added.
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PMID:Functional interactions of lipids and proteins in rat intestinal microvillus membranes. 3 92

A subcellular fractionation method to isolate simultaneously apical and basolateral plasma membrane fractions from the human adenocarcinoma cell line Caco-2, grown on filter supports, is described. The method employs sucrose-density-gradient centrifugation and differential precipitation. The apical membrane fraction was enriched 14-fold in sucrase-isomaltase and 21-fold in 5'-nucleotidase compared with the homogenate. The basolateral membrane fraction was enriched 20-fold relative to the homogenate in K(+)-stimulated p-nitrophenylphosphatase. Alkaline phosphatase was enriched 15-fold in the apical membrane fraction and 3-fold in the basolateral membrane fraction. Analytical density-gradient centrifugation showed that this enzyme was a true constituent of both fractions, and experiments measuring alkaline phosphatase release following treatment with phosphatidylinositol-specific phospholipase C showed that in both membrane fractions the enzyme was glycosyl-phosphatidylinositol-linked. There was very little contamination of either membrane fraction by marker enzymes of the Golgi complex, mitochondria or lysosomes. Both membrane fractions were greater than 10-fold purified with respect to the endoplasmic reticulum marker enzyme alpha-glucosidase. Protein composition analysis of purified plasma membrane fractions together with domain-specific cell surface biotinylation experiments revealed the presence of both common and unique integral membrane proteins in each plasma membrane domain. The post-synthetic transport of endogenous integral plasma membrane proteins was examined using the devised subcellular fractionation procedure in conjunction with pulse-chase labelling experiments and immunoprecipitation. Five common integral membrane proteins immunoprecipitated by an antiserum raised against a detergent extract of the apical plasma membrane fraction were delivered with the same time course to each cell-surface domain.
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PMID:The post-synthetic sorting of endogenous membrane proteins examined by the simultaneous purification of apical and basolateral plasma membrane fractions from Caco-2 cells. 131 18

Brush-border membranes prepared from proximal and distal human small intestine were characterized with respect to lipid fluidity, lipid composition, and protein-lipid interactions. Steady-state fluorescence polarization and differential polarized phase fluorometry revealed that the "static" and "dynamic" rotational components of fluidity (assessed by r infinity values of 1,6-diphenyl-1,3,5-hexatriene and r values of 12-anthroylstearate, respectively) were greater in the distal membranes compared with their proximal counterparts. The lipid fluidity of distal brush-border membranes was also greater as measured by excimer/monomer fluorescence ratio intensities of pyrene decanoate. A lower molar ratio of cholesterol/phospholipid in the distal membranes was responsible for these regional fluidity differences. Lipid thermotropic transitions were detected at 26-28 degrees C using 1,6-diphenyl-1,3,5-hexatriene in proximal and distal membranes. Arrhenius plots of p-nitrophenylphosphatase and gamma-glutamyl transpeptidase activities demonstrated breakpoints in the vicinity of the lipid thermotropic transition temperatures (28-30 degrees C), whereas maltase and sucrase yielded a single activity slope over the range of 10-40 degrees C. Moreover, 50 mM benzyl alcohol fluidized proximal brush-border membranes and increased p-nitrophenylphosphatase activity in this membrane. This agent also shifted the phase transition temperature of the membrane and breakpoint temperature of this enzymatic activity from approximately 28 degrees C to 19 degrees C. These findings demonstrate that differences in human small intestinal brush-border membrane lipid fluidity and lipid composition exist between proximal and distal regions of this organ. Furthermore, alterations in fluidity and/or lipid composition modulate p-nitrophenylphosphatase and gamma-glutamyl transpeptidase but not sucrase or maltase activities in these membranes.
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PMID:Protein-lipid interactions in human small intestinal brush-border membranes. 259 11

The present study examines the role of cardiac lysosomal enzymes in the pathogenesis of the cardiomyopathy that develops in genetically diabetic C57BL/KsJ db+/db+ mice. Db+/db+ mice and littermate controls were sacrificed as age-matched pairs between 5-26 weeks of age. C57BL/6J ob/ob mice and littermates served as other controls. The hearts were excised, homogenized, and the following enzymatic activities measured: N-Acetyl-beta-glucosaminidase, N-acetyl-beta-galactosaminidase, beta-glucosaminidase, aryl sulphatase, alpha-mannosidase, alpha-glucosidase, beta-galactosidase, beta glucosidase, total p-nitrophenyl phosphatase, acid phosphatase and 5'-phosphodiesterase type IV. There is a progressive decrease in cardiac lysosomal enzyme activities of db+/db+ mice for the period 5-21 weeks of age. All enzyme activity is depressed significantly during the 9-21 week interval with beta-glucuronidase, aryl sulphatase and beta-glucosidase decreased about 40-50%. The decrease in lysosomal enzyme activity can explain the accumulation of large residual bodies and interstitial material in the myocardium of the db+/db+ animals
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PMID:Lysosomal enzymes in experimental diabetic cardiomyopathy. 678 Feb 37

Homogenates of the posterior latissimus dorsi muscle, a phasic muscle, were fractionated by a one-step zonal centrifugation technique into four major organelle populations and cytoplasmic constituents. These were: (1) Plasma membrane fragments with a modal equilibrium density of 1.10 and containing 5'-nucleotidase, alkaline phosphodiesterase, p-nitrophenylphosphatase and acid phosphatase (beta-glycerophosphate was used as the substrate). (2) Sarcoplasmic reticular fragments which could be further subdivided into calcium transport vesicles, with a model equilibrium density of 1.16, that exhibited calcium uptake; K+-ATPase; leucyl-bet-naphthylamidase; acid phosphodiesterase; acid phosphatase (using cytidine monophosphate as the substrate); and sarcoplasmic reticular lysosomes, with a model equilibrium density of 1.18, possessing dipeptidyl-aminopeptidase II, cathepsin D, alpha-glucosidase, N-acetyl-beta-glucosaminidase, and NADH oxidase activity. (3) Mitochondria with a modal equilibrium density of 1.21. (4) Catalase-containing vesicles with a modal equilibrium density of 1.22; and cytoplasmic constituents (modal density of 1.25) with phosphorylase, pyruvate kinase, myosin-ATPase, aldolase, and protein and RNA content. The purity of these organelles was equal to or better than previous efforts, with a 30-fold purification achieved for 5'-nucleotidase and alkaline phosphodiesterase. These results lend support to the hypothesis that the sarcoplasmic reticulum of phasic muscle, in addition to its specialized role in excitation-contraction coupling, represents a multifunctional membrane system, and that, similar to the smooth endoplasmic reticulum of other cells, it includes some membrane-bound lysosomal enzymes and NADH oxidase.
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PMID:Isopycnic-zonal centrifugation of plasma membrane, sarcoplasmic reticular fragments, lysosomes, and cytoplasmic proteins from phasic skeletal muscle. 721 87

The purpose of the present study was to determine the role of cardiac lysosomal enzymes in the pathogenesis of the cardiomyopathy that develops in the genetically diabetic C57BL/KsJ db+/db+ mice. Db+/db+ mice and littermate controls were sacrificed as age-matched pairs between 5 and 26 weeks of age. C57BL/6J ob/ob mice and littermates served as other controls. Following anesthesia, the hearts were excised, homogenized, and the following enzymatic activities measured: N-acetyl-beta-glucosaminidase, N-acetyl-beta-galactosaminidase, beta-glucosaminidase, aryl sulfatase, alpha-mannosidase, alpha-glucosidase, beta-galactosidase, beta-glucosidase, total rho-nitrophenyl phosphatase, acid phosphatase. and 5'-phosphodiesterase type IV. There is a progressive decrease in cardiac lysosomal enzyme activities of db+/db+ mice for the period 5 to 21 weeks of age. All enzyme activity is depressed significantly during the 9- to 21-week interval: alpha-glucosidase, beta-glucosidase, alpha-mannosidase, beta-galactosidase, acid phosphatase, N-acetyl-beta-galactosaminidase, 5'-phosphodiesterase type IV, and total rho-nitrophenyl phosphatase are reduced approximately 10 to 20 per cent, whereas beta-glucosaminidase, aryl sulfatase, and N-acetyl-beta-glucosaminidase are decreased almost 40 to 50 per cent. In contrast, cardiac lysosomal enzymic activity in the ob/ob mice does not differ significantly from controls aside from aryl sulfatase (20 per cent decrease) and beta-glucosidase (10 per cent decrease). This decrease in lysosomal enzyme activity can explain the accumulation of large residual bodies and interstitial material that occurs in the myocardium of the db+/db+ animals as part of the cardiomyopathy.
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PMID:Lysosomal enzymes in the heart of the genetically diabetic mouse. 742 Nov 26

Protein bodies and spherosomes isolated from mature seeds of Sorghum bicolor (Linn.) Moench have measurable activity of acid protease, alpha-glucosidase, beta-glucosidase, beta-galactosidase, phytase, acid pyrophosphatase, p-nitrophenyl phosphatase, and RNase. Protein bodies have largely insoluble activities, and produce soluble protein and soluble amino nitrogen during autolysis. They have the dual function of protein storage and protein catabolism. Spherosomes have considerable amounts of soluble enzymes and autolytically produce soluble amino nitrogen and inorganic phosphate but release little soluble protein. Spherosomes are similar to animal lysosomes but have an additional storage function for protein, phosphorus, and metals. Mature sorghum seed contains the necessary enzymes and substrates to generate two basic metabolites, amino acids and inorganic phosphate.
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PMID:Acid Hydrolases and Autolytic Properties of Protein Bodies and Spherosomes Isolated from Ungerminated Seeds of Sorghum bicolor (Linn.) Moench. 1665 31