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)

In the course of screening amylase inhibitor producing, microorganisms, a strain identified as Streptomyces nigrifaciens NTU-3314 was found to have the highest inhibitor-producing ability among the other isolated strains. This strain was aerobically cultured at 30 degrees C in a 5l jar fermentor with a working volume of 2l. The optimum cultural medium consisted of defatted soybean flake 3.0%, potato starch 4.0%, casein 0.6%, sucrose 0.6%, serine 0.02% and NaCl 0.8% (pH 7.0). With an aeration rate of 1.5 vvm, an agitation speed of 300 rpm and an inoculum of 15% seed (previously grown in seed medium 3), the highest amount of inhibitor was obtained after 24 hours of cultivation. The amylase inhibitor produced had inhibitory effects on both alpha-amylase and glucoamylase, but not on beta-amylase, alpha-glucosidase, beta-glucosidase or dextranase. It was quite stable in 0.1M phosphate buffer (pH 7.0) and nearly 100% of its activity was retained even after boiling at 100 degrees C for 20 min.
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PMID:The microbial production of amylase inhibitor and its application. I. Isolation and cultivation of Streptomyces nigrifaciens NTU-3314. 608 1

The pH optimum of pancreatic alpha-amylase from grain-fed steers was determined to be 6.9, while that of intestinal maltase was established at 5.8. Both assays were found to be linear up to 1 hr of incubation. The V max of pancreatic amylase was determined to be pancreatic amylase was determined to be 1.15 mg of maltose monohydrate produced/hr. Activities of pancreatic and intestinal maltase were not reduced (P greater than .05) during the interval from sample collection from the animal until analysis 4 hr later when tissues were kept on ice. Twenty-four yearling Holstein steers fed either alfalfa hay at a maintenance level of metabolizable energy (ME) intake or corn at one, two or three times the maintenance ME intake level were slaughtered after being fed 106 days. The pancreas was removed alone with sections of the intestine. Specific activity of pancreatic amylase for steers fed the high level of corn was 129% of that for steers fed the alfalfa diet (P greater than .05). Intestinal maltase activity was highest in the jejunum and decreased toward the ileum. Increasing dietary starch intake resulted in no response (P greater than .05) in maltase activity at 10, 30, 50, 70, or 90% of the small intestine length. The effect of dietary starch level on dieesta pH was dependent on sampling location within the small intestine. There were no dietary effects (P greater than .05) on digesta pH for the first 10% segment of intestine distal to the pylorus. However, in all subsequent sections, digesta pH was higher steers fed the alfalfa diet than for those fed the two higher levels of grain. A calculation for estimating th amount of pancreatic amylase needed to hydrolyze starch presented to small intestine is discussed.
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PMID:Effect dietary corn starch intake on pancreatic amylase and intestinal maltase and pH in cattle. 616 10

An enzymatic assay for the determination of alpha-amylase in serum was developed which employed a soluble substrate, maltoheptaose, and a coupled enzymatic indicator reaction consisting of alpha-glucosidase and the hexokinase-glucose-6-phosphate dehydrogenase system. We used high-performance liquid chromatography (HPLC) to establish the action pattern of maltoheptaose under the test conditions: (A) the action pattern of alpha-amylase, (B) that of the combined action of alpha-amylase and alpha-glucosidase. Conductive to this effect was: the availability of pure maltoheptaose and human pancreatic alpha-amylase; the development of an adequate procedure for sample pretreatment (partition chromatography on a mixed-bed ion exchange) and of an HPLC system for separation of substrate and reaction products without interference from by products of the assay (partition chromatography on a cation-exchange column with acetonitrile-water); and the use of a new, very sensitive refractometric detector revealing sugar amounts as low as 40 ng. We derived the following stoichiometric equations: (see formula index).
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PMID:Action pattern of human pancreatic alpha-amylase on maltoheptaose, a substrate for determining alpha-amylase in serum. 616 29

The amylolytic activity and especially the production of alpha-amylase (EC 3.2.1.1) and alpha-glucosidase (EC 3.2.1.20) was screened in imperfect fungi, mucoral fungi and some ascomycetes. The character of the polysaccharide system, which is responsible for the utilization of alpha (1 to 4) glucan, was specified with a concomitant screening of growth on soluble starch. The amylolytic activity was found in 29 strains out of the 49 tested.
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PMID:Production of alpha-amylase by microscopic fungi. 616 99

The mode of inhibition of a new complex oligosaccharide that inhibits the alpha-glucoside hydrolase activity of pancreatic and salivary alpha-amylase was studied. Kinetic analysis revealed a non-competitive type of inhibition with a Ki of 1.47 +/- 0.03 micrograms when tested against human pancreatic alpha-amylase and 3.89 +/- 0.08 micrograms against human salivary alpha-amylase. The inhibitory action of alpha-glucoside hydrolase inhibitor (alpha-GHI) on pancreatic amylase was observed over a wide range of pH (6.0--7.9), whereas the inhibition of salivary amylase was optimal at pH 6.5. Column chromatographic investigations suggested the possible formation of an enzyme-inhibitor complex because the mixture of alpha-GHI and pancreatic alpha-amylase was eluted as a single component through a Sephadex G200 column. However, this enzyme-inhibitor complex was easily separated into each component and the enzyme activity was fully recovered after electrophoresis.
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PMID:Effect of alpha-glucosidase inhibitor on human pancreatic and salivary alpha-amylase. 617 67

Kinetic and "high-pressure" liquid-chromatographic studies were performed on the reaction of human pancreatic and salivary alpha-amylase (EC 3.2.1.1) with p-nitrophenyloligosaccharides containing four to seven glucose units. The kinetic studies indicate that, as the temperature increases from 25 to 37 degrees C, the apparent Km of the enzyme for a given substrate increases slightly. However, as the number of glucose units in the substrate increases, the apparent Km decreases. The apparent Vmax increases as the temperature increases, and decreases as the number of glucose units in the substrate increases. In contrast, chromatographic data indicate that the relative rate of hydrolysis by alpha-amylase is pG7 greater than pG6 greater than pG5 greater than pG4. The differences between the kinetic and the chromatographic results are discussed. p-Nitrophenyl-alpha-maltopentaoside and p-nitrophenyl-alpha-maltohexaoside are superior to the other p-nitrophenyloligosaccharides as substrates for determining alpha-amylase activity in an alpha-glucosidase-coupled assay system.
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PMID:Hydrolysis by human alpha-amylase of p-nitrophenyloligosaccharides containing four to seven glucose units. 617 44

We evaluated the enzymic mechanism by which alpha-4-nitrophenyl maltoheptaoside serves as a substrate for serum amylase (EC 3.2.1.1). Because polymeric substrates possess many potential sites of cleavage, the expression of enzymic activity as the number of micromoles of substrate transformed under defined conditions by an enzyme must be changed to "one microequivalent of group transformed." Therefore, we measured the activity of the isoenzymes of alpha-amylase with regard to suitable oligosaccharide substrates, which allowed us to express the catalytic activity in IUB units (U). By "high-performance" liquid chromatography we investigated the mechanism of human pancreatic and salivary alpha-amylase action, both alone and in combination with alpha-glucosidase (EC 3.2.1.20). On the basis of these results, we can describe exactly the entire reaction sequence and determine the stoichiometric coefficient of 4-nitrophenol within 0.02 mol/L (SD) produced under the assay conditions.
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PMID:Mechanism of action of human pancreatic and salivary alpha-amylase on alpha-4-nitrophenyl maltoheptaoside substrate. 618 12

High performance liquid chromatography (HPLC) was used to monitor the purity of the substrates and to establish the patterns of hydrolysis of ortho- and para-nitrophenylmaltooligosaccharides (2-7 glucose residues) catalysed by human pancreatic and salivary alpha-amylase. Separation of the reaction products from the remaining substrate was performed on a TSK-G-2000 PW or a RP18 column. By measuring the quantitative distribution of products, and assuming a 5-subsite model for the active site of alpha-amylase, differential activities for the hydrolysis of the different glycosidic bonds in the 2 series of substrates were deduced. A highly sensitive coupled continuous assay system is based on the formation of phenyloligosaccharides with 1-4 glucose residues by the action of the amylase under test, coupled to hydrolysis of these products by yeast alpha-glucosidase. The most suitable test substrates were shown to be para-nitrophenyl-alpha-D-maltotetraoside and -pentaoside. Direct production of nitrophenol from ortho-nitrophenyl-alpha-D-maltotrioside is recommended for the measurement of the alpha-amylase activity of pancreatic and salivary gland secretions and extracts.
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PMID:Action pattern of human pancreatic and salivary alpha-amylase on 1,4-alpha-D-nitrophenylmaltooligosaccharides. 1,4-alpha-D-nitrophenylmaltooligosaccharides as substrates of alpha-amylse, I. 618 88

Alpha-glucosidase was membrane bound during exponential growth of Bacillus licheniformis but was released into the medium during stationary phase. It could be partially removed from exponential phase cells by washing with NaCl (0.5 M). Alpha-Amylase was exclusively extracellular and could not be detected in cells. Polysomes were prepared from exponential phase cells and separated into membrane bound and soluble fractions. In vitro chain completion and immunoprecipitation showed that alpha-glucosidase and alpha-amylase were synthesized by membrane bound and not by soluble ribosomes.
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PMID:Synthesis of alpha-amylase and alpha-glucosidase by membrane bound ribosomes from Bacillus licheniformis. 619 21

Failure to develop clear-cut, distinguishing characteristics for hydrophobic and hydrophilic forms of maltase-glucoamylase led us to attempt the purification of the detergent-extracted enzyme in the continuous presence of protease inhibitors (phenylmethylsulfonyl fluoride and N-ethylmaleimide). The enzyme was purified by molecular exclusion, anion-exchange, and affinity column chromatography to a final specific maltase activity of 80 U/mg protein, comparable to previously solubilized enzymes. Both detergent (d-maltase) and proteolytically (p-maltase) solubilized enzymes had identical Km's for maltose and similar glycogenase activity. d-Maltase was clearly amphipathic. Whereas 95% of p-maltase was eluted with aqueous buffer from an octyl-Sepharose CL-4B column, the elution of d-maltase required solutions containing Triton X-100 and ethylene glycol. On density gradient centrifugation and sodium dodecyl sulfate (SDS)--polyacrylamide gels, p-maltase migrated as one high molecular weight species of 500,000. In contrast d-maltase migrated heterogeneously and the smallest maltase-active forms delineated by these two techniques, as well as by high pressure liquid chromatography, had molecular weights which ranged from 120,000 to 15,0000. Both p- and d-maltase were dissociated by heat in SDS, forming five prominent species as we have previously described. In contrast to p-maltase, in which the smallest species, band 1, equalled 36.7% of the total mass, band 1 of d-maltase accounted for 66.5%. Band 1 was separable when smaller amounts of enzyme were applied to slab gels and stained with silver, into two proteins of 130,000 and 145,000 daltons. The 145,000 dalton protein was absent in p-maltase and was replaced by a faint band of 140,000 daltons.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rat intestinal maltase--glucoamylase. Purification of the detergent-solubilized enzyme in the presence of protease inhibitors: properties and identification of a protease-sensitive subunit. 642 12


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