Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Three forms of alpha-glucosidase, I, II, and III, have been purified from the whole body extract of adult flies of Drosophila melanogaster in yields of 2.1, 5.3, and 6.7%, respectively. The purification procedures involved ammonium sulfate fractionation, Con A-Sepharose 4B affinity chromatography, DEAE-Sepharose CL-6B ion exchange chromatography, Sephacryl S-200 gel filtration, and preparative gel electrophoresis. Each purified enzyme showed a single band on polyacrylamide gel on both protein and enzyme activity staining. The molecular weights of alpha-glucosidases I, II, and III were estimated to be 200,000, 56,000, and 76,000, respectively, by gel filtration. SDS gels indicated that alpha-glucosidases II and III were each composed of a single polypeptide chain, whereas alpha-glucosidase I was composed of two identical subunits. Both alpha-glucosidases II and III hydrolyzed sucrose and p-nitrophenyl-alpha-D-glucoside (PNPG), but alpha-glucosidase I hydrolyzed PNPG to a much lesser extent than sucrose. For sucrose the pH optima of alpha-glucosidases I, II, and III were pH 6.0, 5.0, and 6.0 and the Km values were 13.1, 8.9, and 10 mM, respectively. For PNPG the pH optima of alpha-glucosidases II and III were pH 5.5 and 6.5 and the Km values were 0.77 and 0.21 mM, respectively.
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PMID:Purification and partial characterization of three forms of alpha-glucosidase from the fruit fly Drosophila melanogaster. 10 85

An alpha-glucosidase was purified from baker's yeast. The molecular weight was approximately 44 000 daltons. SDS-disc gel electrophoresis suggested that the enzyme consisted of four subunits. The isoelectric point was at pH 5.4. The Km values for p-nitrophenyl alpha-D-glucopyranoside and maltose were 2.9 X 10(-4) and 2.5 X 10(-2) M, respectively. Binding of 2-(p-toluidino)naphthalene-6-sulfonate to the alpha-glucosidase was associated with a strong increase in fluorescence. The dissociation constant of the enzyme-TNS complex was 8 X 10(-5) M. The fluorescent probe did not interfere with the binding of glucose to the enzyme although the alpha-glucosidase was inhibited by high concentrations of TNS. The formation of an enzyme-glucose complex was indicated by an increase of fluorescence and by a shift in the wavelength for maximal emission which suggests that the binding process is associated with a change in conformation. The dissociation constant of the glucose--alpha-glucosidase complex KD = 0.57 X 10(-3) M, was calculated from the increase in fluorescence as a function of glucose concentration.
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PMID:On the properties of alpha-glucosidase and the binding of glucose to the enzyme. 36 Jul 36

Turnover in organ culture of human small intestinal membrane glycoproteins was measured by the pulse-chase technique, using 14C-glucosamine, 14C-fucose or 14C-leucine as tracers. Apparently, low degradation rates were found for the major high-molecular-weight proteins which co-migrated on SDS-polyacrylamide gels with maltase-glucoamylase, lactase-phlorizin-hydrolase and sucrase-isomaltase enzymic activities. In contrast, an unidentified glycoprotein appearing on gels next to alkaline phosphatase exhibited a higher degradation rate with an apparent half-life of about 30 h, this being similar to the half-life of total glycoprotein as measured in mucosal homogenates. The results obtained with the pulse-chase technique were confirmed by double isotope experiments using 14C-leucine and 3H-leucine as tracers. These findings indicate that in organ culture there is a low basic turnover of human intestinal membrane glycoproteins which co-migrate on gels with known glycosidase enzymic activities.
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PMID:Turnover studies of human intestinal brush border membrane glycoproteins in organ culture. 45 41

A highly thermostable alpha-glucosidase (E C.3.2.1.20) from an extreme thermophile, Thermus thermophilus HB 8, was purified to homogeneous by ammonium sulfate fractionation, DEAE-cellulose chromatography and preparative slab gel electrophoresis. The enzyme was purified 17 fold with 21% recovery of activity. The enzyme had a molecular weight of 67000 by SDS-PAGE. The isoelectric point was pH4.5 by IEF on PAG. The enzyme hydrolized p-nitrophenyl-alpha-glucoside (PN-PG), sucrose and maltose, but not cellobiose, melibiose and soluble starch. The km value for PNPG was 0.4mmol/L, the Vmax was 0.29 mumol.min-1.mg-1. The enzyme exhibited high thermostability. After incubation at 90 degrees C for 10 h in 50 mmol/L acetate buffer pH 5.8, the enzyme retained 90% of its original activity. The half-live (t1/2) at 95 degrees C was 108 min. The enzyme was activated by Mg2+, Mn2+, Ca2+, Ba2+ and strongly inhibited by Hg2+, Cu2+. Modification of the enzyme by EDC or DEPC led to complete loss of activity, which suggests that carboxyl group(s) and histidine residue(s) are essential for activity of alpha-glucosidase.
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PMID:[Purification and characterization of alpha-glucosidase from an extreme thermophile, Thermus thermophilus HB 8]. 141 35

The common hookworm (Ancylostoma ceylanicum) infection of humans was studied in golden hamsters model system. Significant biochemical modulations were observed in hamster jejunal brush border membrane (BBM), the primary site of infection. Analysis of BBM at the peak of infection (3-weeks) revealed a marked decrease in the activities of sucrase, lactase and maltase, while activities of alkaline phosphatase, (Ca2+ + Mg2+)-ATPase and gamma-glutamyl transpeptidase were increased. Kinetic studies conducted with maltase, a superficially localised enzyme of jejunal BBM, revealed loss of enzyme active site during the infection. Among other constituents, the levels of cholesterol and triglycerides were significantly decreased with slight increase in phospholipid content in the infected animals. The hookworm infection also caused a decline in total hexose content indicating an altered membrane glycocalyx. Conversely, there was significant enhancement of hydroxyproline and sialic acid contents. SDS-PAGE analysis showed an enhancement in both low and high molecular weight proteins in jejunal BBM preparations of the infected group. Gel electrophoresis of glycoproteins further revealed the appearance of two additional peaks in the low molecular weight region and concomitant disappearance of a peak in the high molecular weight region. These results strongly support the view that the hookworm infection causes severe damage not to the site of attachment alone but also to the entire cell lining of the jejunum and therefore could influence overall digestion and absorption.
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PMID:Biochemical analysis of jejunal brush border membrane of golden hamster: pathogenic modulations due to ancylostomiasis. 159 19

To clarify the enzyme participates in maltotriose synthesis, we purified maltase from rabbit kidney using 2-amino-2-hydroxymethylpropane-1,3-diol (Tris) affinity column chromatography. The purified enzyme possessed specific activity of 33.7 mumol/mg/min and estimated molecular weight of 350,000 dalton, as judged by SDS-polyacrylamide gel electrophoresis, comparable with those reported from rat kidney. Moreover this enzyme possessed not only maltase (maltose----glucose) but also amylomaltase (maltose----maltotriose) activity, and both activities were inhibited by Tris in a dose-dependent manner with similar IC50 values. From these results, we concluded that maltotriose was synthesized by maltase in vitro and that kidney maltase may participate in sugar metabolism in vivo.
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PMID:Synthesis of maltotriose by maltase purified from rabbit kidney. 177 60

Intestinal brush borders from Wistar rats contained a total of 20-30-times more binding sites for Escherichia coli heat-labile enterotoxin (LT-1) than for cholera toxin (CT). The results suggest that LT-1 binds to sites in addition to ganglioside GM1, the binding site for CT. Brush border proteins were separated by SDS-PAGE, blotted to nitrocellulose and the filters incubated with 125I-labeled toxins. [125I]LT-1 was shown to bind to a series of brush border galactoproteins ranging in size from 130-140 kDa. Binding was inhibited by unlabeled LT-1 (but not CT), and by ricin and free galactose. A number of brush border enzymes are large glycoproteins which can be solubilised by papain. The papain-solubilised sucrase-isomaltase complex was purified by affinity chromatography and shown to bind LT-1, as did the proteins in fractions enriched in maltase activity. However, such brush border galactoproteins do not account for all of the additional LT-1 binding sites. Thus, brush borders prepared from 1-15-day-old rabbits contained many more binding sites for LT-1 than CT despite the absence of any sucrase-isomaltase activity, and no [125I]LT-1 binding proteins could be detected by blotting. There was a marked variation in the number of LT-1 binding sites in different strains of rat, and between different species.
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PMID:Characterisation of the binding sites for Escherichia coli heat-labile toxin type I in intestinal brush borders. 193 71

Acid alpha-glucosidase purified from pig liver showed heterogeneity in its affinity to Sephacryl S-200 gel. Acid alpha-glucosidase was separated into two fractions (S1 and S2) by Sephacryl S-200 affinity chromatography. Each fraction contained components at apparent 76 kDa and 67 kDa on SDS/PAGE. The amount of S1 fraction was about 1.3 times that of the S2 fraction. In the kidney the ratio of S1 to S2 fraction was similar to that in the liver. However, the heart contained 1.3 times as much S2 fraction as S1 fraction. The spleen acid alpha-glucosidase consisted mainly of S1 fraction, containing only a 76 kDa component. Immunohistochemically, acid alpha-glucosidase was demonstrated in the macrophages of the spleen. Thus the 76 kDa component in the spleen must come mainly from the macrophages. Lectin-binding analysis was carried out on the components present in the S1 and S2 fractions after electrophoresis and transfer to nitrocellulose sheets. Slight differences in binding observed suggest differences in the structure of the sugar side chains.
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PMID:Heterogeneity of pig lysosomal acid alpha-glucosidase. Affinity to Sephacryl S-200 gel and tissue distribution. 195 64

Brush border fragments (BBF) were isolated from homogenates of intestinal epithelium prepared from four groups of tadpoles: premetamorphic larvae, thyrostatic larvae, spontaneously metamorphosed larvae, and triiodothyronine (T3)-induced froglets. Isolation was accomplished by a combination of both Ca2+ precipitation and differential centrifugation methods. These preparations were routinely enriched seven- to-eleven-fold for the two amphibian brush border marker enzymes, gamma-glutamyltransferase and maltase. Comparison by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with silver staining revealed the presence of a polypeptide of Mr 27,000 only after spontaneous and T3-induced metamorphosis. One-dimensional SDS-PAGE together with lectin staining showed six strongly concanavalin A reactive polypeptides (Mr 52,000, 57,000, 65,000, 80,000, 130,000 and 150,000) in both preparations examined. Immunoblot analyses allowed us to detect in both preparations the presence of villin (Mr 105,000), a cytoskeletal component of microvilli. Two-dimensional isoelectric focusing IEF/SDS-PAGE together with silver staining showed the polypeptides of Mr 41,500, 43,000, 60,500 and 101,000 to be specific components of the primary intestinal epithelium brush border. In contrast six polypeptides of Mr 27,000, 52,000, 58,000, 59,000 and 95,000 were only detected in intestinal BBF after spontaneous and T3-induced metamorphosis. Their presence is under the control of the thyroid hormone. The results provide new insight regarding the subcellular localization of polypeptides whose synthesis changes during spontaneous (Figiel et al., 1987) and T3-induced metamorphosis (Figiel et al., 1989).
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PMID:Influence of triiodothyronine on the polypeptide composition of the intestinal brush border membrane during amphibian metamorphosis. 198 Nov 41

A detergent solubilised sucrase from monkey small intestine has been purified 388-fold to gel electrophoretic homogeneity with an overall recovery of 36%. The molecular weight of the enzyme was 263 kDa by gel filtration. Electrophoresis in the presence of SDS indicates that the enzyme is a hetero-dimer. Mixed substrate inhibition studies and inhibition by PCMB and Tris suggest the presence of two catalytically active sites in the form of maltase and sucrase with isomaltase activity being common to both sites. Polyclonal antiserum against the purified enzyme showed a single continuous precipitin line with the purified antigen.
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PMID:Some properties of monkey intestinal sucrase. 211 33


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