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)

The gene coding for a thermostable exo-alpha-1,4-glucosidase (alpha-glucoside glucohydrolase: EC 3.2.1.20) of Bacillus stearothermophilus ATCC 12016 was cloned within a 2.8-kb AvaI fragment of DNA using the plasmid pUC19 as a vector and Escherichia coli JM109 as a host. E. coli with the hybrid plasmid accumulated exo-alpha-1,4-glucosidase mainly in the cytoplasm. The level of enzyme production was about sevenfold higher than that observed for B. stearothermophilus. The cloned enzyme coincided absolutely with the B. stearothermophilus enzyme in its relative molecular mass (62,000), isoelectric point (5.0), amino-terminal sequence of 15 residues (Met-Lys-Lys-Thr-Trp-Trp-Lys-Glu-Gly-Val-Ala-Tyr-Gln-Ile-Tyr-), the temperature dependency of its activity and stability, and its antigenic determinants.
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PMID:Cloning and expression of a thermostable exo-alpha-1,4-glucosidase gene from Bacillus stearothermophilus ATCC12016 in Escherichia coli. 136 46

Honeybee alpha-glucosidase I was inactivated with diethylpyrocarbonate (DEPC). The inactivation followed pseudo-first-order kinetics. The rate of the loss of activity was decreased by the addition of a substrate, maltose. Since there was no spectral change in the tyrosine absorption region, it was recognized that DEPC did not react with this residue. The alpha-glucosidase had one free sulfhydryl group, which was not involved in the catalytic reaction, and was not modified by DEPC. On the other hand, the specific reaction of DEPC with a histidyl residue was spectrophotometrically confirmed by an increase in absorption near 240 nm, and the activity of the inactivated enzyme was restored by hydroxylamine. The modification rate of one histidyl residue by DEPC was almost equal to the rate of the activity loss. These results indicate that there is one histidyl residue at or near the catalytic site, and that honeybee alpha-glucosidase I has a single active site.
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PMID:Evidence for a single catalytic site of honeybee alpha-glucosidase I by chemical modification with diethylpyrocarbonate. 142 1

Twelve sulphonylurea-treated Type 2 diabetic patients underwent treatment for 2-week periods with the absorbable alpha-glucosidase inhibitor BAY m1099 (50 mg thrice daily) and with guar granules (5 g thrice daily) separately and together in a sequence-randomized double-blind placebo-controlled study. BAY m1099 and guar reduced the mean fasting plasma glucose from 10.0 +/- 0.7 mmol l-1 to 8.7 +/- 0.5 (p less than 0.05) and 8.3 +/- 0.7 mmol l-1 (p less than 0.01), respectively. Both agents also lowered home-monitored postprandial blood glucose, with BAY m1099 exerting the greater effect. Guar, but not BAY m1099, lowered serum cholesterol from 5.43 +/- 0.52 to 5.29 +/- 0.31 mmol l-1 (p less than 0.05). BAY m1099 reduced the test breakfast plasma responses of glucose (p less than 0.001) and gastric inhibitory polypeptide (GIP, p less than 0.01) and increased those of peptide tyrosine-tyrosine (p less than 0.05) and motilin (p less than 0.01). Guar also reduced plasma glucose concentrations after a test breakfast (p less than 0.05) and increased the response of neurotensin (p less than 0.05). Combining treatments gave no further reduction of postprandial blood glucose concentration and was associated with an increased incidence and severity of gastrointestinal side-effects.
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PMID:Effects of alpha-glucosidase inhibition and viscous fibre on diabetic control and postprandial gut hormone responses. 216 5

Protein sulfation in small intestinal epithelial cells was studied by labelling of organ cultured mucosal explants with [35S]-sulfate. Six bands in SDS-PAGE became selectively labelled; four, of 250, 200, 166 and 130 kd, were membrane-bound and two, of 75 and 60 kd, were soluble. The sulfated membrane-bound components were all enriched in the microvillar fraction but either absent or barely detectable in intracellular or basolateral membranes. Immunopurification of sucrase-isomaltase, maltase-glucoamylase, aminopeptidase N and aminopeptidase A showed that these microvillar enzymes become sulfated. Most if not all the sulfate was bound to tyrosine residues rather than to the carbohydrate of the microvillar enzymes, showing that this type of modification can occur on plasma membrane proteins as well as on secretory proteins.
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PMID:Tyrosine sulfation, a post-translational modification of microvillar enzymes in the small intestinal enterocyte. 312 1

Over 24-h culture with hydrocortisone (400 nM), activity of brush-border alkaline phosphatase, alpha-glucosidase, and leucyl-2-naphthylamidase and cytoplasmic-mitochondrial malate dehydrogenase increased (P less than 0.05) by 80-133% compared with controls. Uptake of 3-O-methyl-D-[14C]glucose after 24-h culture was increased (P less than 0.05) by 30% compared with cultures without hydrocortisone. Labeling of protein with L-[14C]tyrosine and glycoprotein with D-[3H]glucosamine increased (P less than 0.05) by 40 and 88%, respectively, with hydrocortisone. The effects of hydrocortisone were dose dependent at normal serum concentrations (100-600 nM) and not further stimulated by larger concentrations. Cytoplasmic lactate dehydrogenase and lysosomal hexosaminidase activity, specific radioactivity of soluble precursor pools for protein and glycoprotein labeling, incorporation of [3H]thymidine into DNA, and morphology were unaffected by hydrocortisone. Inhibitors of glucocorticoid receptor binding (progesterone), mRNA transcription (alpha-amanitin), and protein synthesis (cycloheximide) prevented the effects of hydrocortisone. We suggest that hydrocortisone maintains the digestive, absorptive, and cellular function of cultured human jejunum. These protective effects were associated with increased protein synthesis and glycosylation and dependent on a classical steroid-hormone mechanism.
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PMID:Protection of epithelial function in human jejunum cultured with hydrocortisone. 634 19

alpha-Glucosidase II of the facultative thermophile Bacillus thermoamyloliquefaciens KP1071 (FERM-P8477; growth over 30-66 degrees C) was purified to a homogeneous state. Its M(r) was estimated as 90000 by SDS/PAGE. However, the enzyme behaved as an active Mr 540000 protein on gel filtration with each of two gels of different matrices as well as on gel electrophoresis under native conditions. The enzyme was not glycosylated. Its isoelectric point was estimated as 5.7. The N-terminal sequence of 20 residues was determined asAla1-Ile-Gln-Pro-Glu-Gln-Asp-Asp-Lys-Thr-Gln-Glu-Asp-Gly- Tyr-Ile-Asp-Ile-Gly-Asn20. The sequence did not resemble those of procaryotic and eucaryotic proteins hitherto reported including the monomeric exo-alpha-1,4-glucosidase and the monomeric oligo-1,6-glucosidase from the same microorganism. The alpha-glucosidase II had no antigenic group shared with the latter two enzymes. Analysis of substrate specificity showed that the alpha-glucosidase II has dual activity towards oligo-1,6-glucosidases and exo-alpha-1,4-glucosidases, but its preference is for non-reducing terminal alpha-1,4 glucosidic bonds in substrates. Kinetic studies proved that both activities are attributed to the same catalytic site. The enzyme was most active at 81 degrees C and pH 7.0. Its half-life at pH 6.8 was 10 min at 81 degrees C, and 5 h at 55 degrees C in 6.4 M urea, 26% ethanol or 2.5% SDS. We suggest that the alpha-glucosidase II is a thermostable, homohexameric enzyme of origin distinct from the exo-alpha-1,4-glucosidase and the oligo-1,6-glucosidase present in the same strain.
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PMID:Bacillus thermoamyloliquefaciens KP1071 alpha-glucosidase II is a thermostable M(r) 540,000 homohexameric alpha-glucosidase with both exo-alpha-1,4-glucosidase and oligo-1,6-glucosidase activities. 912 33

We report here the isolation of alpha-glucosidase (AGH) inhibitory peptides derived from sardine muscle hydrolyzate, which was prepared by digestion with Bacillus licheniformis alkaline protease. As a result of reversed-phase HPLC purification, two AGH inhibitory peptides were isolated from a DEAE-Sephadex A-25 column eluate. The peptides were identified as follows: Val-Trp (IC50 = 22.6 mM) and Try-Tyr-Pro-Leu (IC50 = 3.7 mM). AGH inhibitory studies of Try-Tyr-Pro-Leu and its derivatives demonstrated the importance of the tri-peptide chain length as well as the hydrophobic aromatic amino acid tyrosine at the N-terminus, aliphatic amino acids at the C-terminus, as well as an amide proton from the peptide chain at the middle position of the tri-peptide to develop AGH inhibition activity.
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PMID:Isolation and identification of peptidic alpha-glucosidase inhibitors derived from sardine muscle hydrolyzate. 1040 29

Alpha-glucosidase I initiates the trimming of newly assembled N-linked glycoproteins in the lumen of the endoplasmic reticulum (ER). Site-specific chemical modification of the soluble alpha-glucosidase I from yeast using diethylpyrocarbonate (DEPC) and tetranitromethane (TNM) revealed that histidine and tyrosine are involved in the catalytic activity of the enzyme, as these residues could be protected from modification using the inhibitor deoxynojirimycin. Deoxynojirimycin could not prevent inactivation of enzyme treated with N-bromosuccinimide (NBS) used to modify tryptophan residues. Therefore, the binding mechanism of yeast enzyme contains different amino acid residues compared to its mammalian counterpart. Catalytically active polypeptides were isolated from endogenous proteolysis and controlled trypsin hydrolysis of the enzyme. A 37-kDa nonglycosylated polypeptide was isolated as the smallest active fragment from both digests, using affinity chromatography with inhibitor-based resins (N-methyl-N-59-carboxypentyl- and N-59-carboxypentyl-deoxynojirimycin). N-terminal sequencing confirmed that the catalytic domain of the enzyme is located at the C-terminus. The hydrolysis sites were between Arg(521) and Thr(522) for endogenous proteolysis and residues Lys(524) and Phe(525) for the trypsin-generated peptide. This 37-kDa polypeptide is 1.9 times more active than the 98-kDa protein when assayed with the synthetic trisaccharide, alpha-D-Glc1,2alpha-D-Glc1,3alpha-D-Glc-O(CH2)(8)COOCH(3), and is not glycosylated. Identification of this relatively small fragment with catalytic activity will allow mechanistic studies to focus on this critical region and raises interesting questions about the relationship between the catalytic region and the remaining polypeptide.
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PMID:Binding residues and catalytic domain of soluble Saccharomyces cerevisiae processing alpha-glucosidase I. 1601 48

We designed and synthesized polyhydroxylated pyrrolidines 1-12 from L-tyrosine, L-phenylalanine, and D-tyrosine through iodine-mediated intramolecular cyclization followed by Woodward-Prevost reaction. The synthetic polyhydroxylated pyrrolidines were identified with structure-based inhibitory activity and selective inhibitory activity against alpha-rhamnosidase. (2S,3S,4R)-deacetyl anisomycin 7 was the best inhibitor among the 12 polyhydroxylated pyrrolidines because it possesses the same stereoconfiguration at C1, C2, C3 as alpha-L-rhamnopyranoside. An investigation into the nature of the inhibition showed that the synthetic pyrrolidines are competitive inhibitors. They also did not have remarkable inhibitory activity against seven glycosidases (alpha-glucosidase, alpha-mannosidase, alpha-amylase, beta-glucosidase, beta-galactosidase, beta-amylase, and invertase).
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PMID:Alpha-rhamnosidase inhibitory activities of polyhydroxylated pyrrolidine. 1603 52

A new tyrosine-derived metabolite, aspergillusol A (4), was isolated on a gram scale, together with a methyl ester of 4-hydroxyphenylpyruvic acid oxime (5) and secalonic acid A, from the marine-derived fungus Aspergillus aculeatus CRI323-04. The tetraol in 4 was identified as erythritol by comparison of the 1H NMR spectrum of its benzoylated derivative with those of benzoylated erythritol (7) and D-threitol (8), as well as by cellulose-based chiral HPLC analysis. Aspergillusol A (4) selectively inhibited alpha-glucosidase from the yeast Saccharomyces cerevisiae, but it was inactive toward the alpha-glucosidase from the bacterium Bacillus stearothermophilus.
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PMID:Aspergillusol A, an alpha-glucosidase inhibitor from the marine-derived fungus Aspergillus aculeatus. 1982 18


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