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)

Using standard growth conditions (LB medium, 37 degrees C, induction with 5 mM IPTG) yeast alpha-glucosidase PI expressed under the control of the regulated tac-hybrid promoter results in the synthesis of insoluble aggregated alpha-glucosidase granules in Escherichia coli. Under these conditions active soluble alpha-glucosidase amounts to less than 1% of the heterologously produced protein. However, the amount of soluble active alpha-glucosidase was dramatically increased when the strong tac-hybrid promoter was to a limited extent induced. This was achieved at concentrations of 0.01 mM IPTG or of 1% lactose or lower in a lactose-permease deficient host strain containing the lacIq repressor gene on an R-plasmid. The formation of active soluble alpha-glucosidase was almost 100% when E. coli cells induced in this manner were cultivated under conditions that reduced growth rate, i.e. at decreased temperature, extreme pH values or in minimal and complete media supplemented with different carbon sources.
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PMID:Control of formation of active soluble or inactive insoluble baker's yeast alpha-glucosidase PI in Escherichia coli by induction and growth conditions. 265 69

Juvenile white sturgeon were fed isonitrogenous diets containing 27.2% glucose, fructose, maltose, sucrose, lactose, dextrin, raw corn starch or cellulose for 8 wk. Growth, body composition, plasma chemistry (with the exception of glucose), and liver glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49), malic enzyme (EC 1.1.1.40) and isocitrate dehydrogenase (ICDH, 1.1.1.42) activities of sturgeon were significantly (P less than 0.05) affected by the different dietary carbohydrate sources. Sturgeon fed either the maltose or glucose diets had the highest percent energy retained, followed by those fed either the dextrin, raw corn starch or sucrose diets, whereas those fed either the lactose, fructose or cellulose diets had the lowest. Sturgeon fed either the maltose or glucose diets were hyperlipidemic, having twice the amount of plasma total lipid, triacylglycerol and total cholesterol as fish fed the other carbohydrate sources. These two carbohydrate sources were also more lipogenic: maltose- or glucose-fed sturgeon had significantly higher body lipid and liver G6PDH, malic enzyme, and ICDH activities. The poor ability of sturgeon to utilize either sucrose or lactose appears to be due to low intestinal sucrase (EC 3.2.1.48) and lactase (EC 3.2.1.108) activities. Intestinal aminopeptidase (EC 3.4.11.11), maltase (EC 3.2.1.20), sucrase and lactase activities of sturgeon were not affected by feeding different carbohydrate sources for 8 wk.
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PMID:Ability of juvenile white sturgeon (Acipenser transmontanus) to utilize different carbohydrate sources. 272 21

To investigate further the pathophysiology of rotavirus-induced diarrhea, changes in specific activities of eight relevant intestinal enzymes [alkaline phosphatase, thymidine kinase, lactase, maltase, sucrase, Na+,K+-adenosine triphosphatase (ATPase), adenylate and guanylate cyclases] were measured following infection of suckling mice with murine rotavirus (epizootic diarrhea of infant mouse strain) and compared with age-matched control mice. The concentration of lactose within the lumen of the gastrointestinal tract during infection was also measured. During the course of infection, activities of alkaline phosphatase and lactase decreased, whilst the activity of thymidine kinase increased. Precocious maturation profiles of sucrase and maltase enzymes were observed. No significant changes were detected in the activities of Na+,K+-ATPase or the adenylate and guanylate cyclases. These results are discussed in relation to existing and novel hypotheses on the pathogenesis of rotavirus-induced diarrhea.
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PMID:Intestinal enzyme profiles in normal and rotavirus-infected mice. 289 74

The tests with lactose loading followed by the assay of blood sugar were conducted in 500 normal subjects, aged from 18 to 89 years, and 262 patients with gastro-intestinal diseases, aged from 25 to 55 years. When lactose malabsorption was detected, aspiration biopsy of the small intestine mucosa was performed followed by the study of the structure and the level of a number of disaccharidases (lactase, maltase, saccharase). Lactose malabsorption was detected in 72 (14.4%) out of 500 normal subjects (10.6%--aged 18-59, and 20%--aged 60-89 years), among them there were 12.5% of Russians, 13% of Byelorussians and 5.8% of Ukrainians (aged 25-55 years). The secondary lactose malabsorption was recorded in 44% of patients with ulcerative colitis, in 33% of patients with chronic enterocolitis, in 11.5% of patients with gastric ulcer, in 8% of those with duodenal ulcer, in 23.5% of patients with chronic gastritis attended by lowered secretory function, and in 8% of those with enhanced secretory function.
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PMID:[Current problems of lactase deficiency]. 296 77

Bacillus stearothermophilus was found to bind strongly to starch and related alpha-glucans at 25 degrees C but not at 55 degrees C. The binding at the lower temperature could be assayed either by binding of fluorescein-labeled amylopectin to washed cell suspensions or through the reversible retention of bacteria by affinity chromatography in matrices containing immobilized starch. The bacteria exhibited amylopectin-dependent agglutination. The binding and agglutination were highest in bacteria grown on substrates containing alpha-1,4-glucosidic linkages such as maltose or dextrins. The binding affinity of cells was highest for maltohexaose, lower for maltose, and low or undetectable for glucose, isomaltose, cellobiose, or lactose. The reduced binding at the higher temperature was due to the rapid breakdown of the alpha-glucosides. The bacteria exhibited an extracellular alpha-amylase activity as well as a cell-associated alpha-glucosidase with high activity at 55 degrees C but undetectable activity at 25 degrees C. The inducibility, specificity, and protease sensitivity of the thermophilic alpha-glucosidase in whole cells were similar to those of the binding activity assayed at the lower temperature. Further evidence linking the binding and alpha-glucosidase activities came from a mutant, selected through affinity chromatography, which was reduced in starch binding at room temperature and also reduced in membrane-associated alpha-glucosidase activity at 55 degrees C. These results suggest a novel survival mechanism whereby a bacterium attaches to a macromolecular substrate under nonoptimal growth conditions for possible utilization upon a shift to more favorable conditions.
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PMID:Temperature-sensitive binding of alpha-glucans by Bacillus stearothermophilus. 308 61

The intestinal first pass metabolism of amygdalin has been investigated in rat small intestine in vitro. The results show that amygdalin is hydrolyzed to prunasin, essentially in the wall of the proximal jejunum. This specific beta(1-6)hydrolytic cleavage of the terminal glucose residue is pH-dependent and can be inhibited by glucono-delta-lactone, a potent inhibitor of the lysosomal beta-glucosidase of the rat intestine. No substrate competition between phloridzin and lactose vs amygdalin was noted. None of the more common soluble beta- or alpha-enzymatic activities of mammalian intestine (alpha-glucosidase, alpha-amylase) or mammalian liver (beta-galactosidase, beta-glucuronidase) were capable of catalyzing the hydrolysis of the terminal glucose from amygdalin at pH's 5.0, 7.0 or 9.0. Furthermore, no metabolic activity of isolated rat livers toward amygdalin and prunasin was observed within two hours of recirculating perfusion. However, cecal contents of conventional rats, exhibited both amygdalin- and prunasin-hydrolyzing activities. The resulting mandelonitrile dissociates spontaneously into cyanide and benzaldehyde. Therefore, our findings indicate that metabolism of amygdalin to prunasin occurring in the proximal part of jejunum is apparently mediated by enzymatic beta(1-6)glucosidase activity of the gut wall. In contrast, the toxicity of amygdalin due to the release of cyanide obviously requires microbiological activities of the gut flora.
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PMID:Intestinal first pass metabolism of amygdalin in the rat in vitro. 308 25

The development of the human fetal gastrointestinal tract takes place early during gestation. The pancreas although developed by morphological means at the 16th week of gestation excretes its exocrine enzymes later at the 24th week of gestation except for amylase which reaches its full activity 6 months after birth. Trypsinogen secreted at the 24th week is activated into trypsin by enterokinase at the 26th week of gestation whereas lipase and colipase are secreted from the 24th week. The small intestine starts developing at the 10th week morphologically and functionally. At the same time when villi and crypts start to develop at the 11th to 12th week the first enzyme activities can be detected, i.e. sucrase-isomaltase, maltase-glucoamylase and lactase. Also peptidases and lysosomal hydrolases are measured at this age. With the exception of lactase, intestinal enzymes reach sufficient activities at the 25th week of gestation. Lactase activity remains low until the 32nd-34th week. For the digestion and absorption of lipids, protein and carbohydrates the gastrointestinal tract of premature infants under 1500 g in rather well equipped. Lipids are hydrolysed by the mutual action of breast milk lipase, lingual lipase, gastric lipase and pancreatic lipase. The carbohydrates lactose and oligosaccharides as supplements to breast milk are hydrolysed by lactase, sucrase-isomaltase and maltase-glucoamylase. Breast milk proteins and cows milk hydrolysates are digested by pancreatic proteases into oligopeptides which can be hydrolysed within the lumen by brush border peptidases and be absorbed. Peptides also can actively be transported through the microvillus membrane and be hydrolyzed by intracellular peptidases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Nutrition of premature infants below 1,500 g: enteral prerequisites]. 309 34

The effects of the aqueous phase of human breast milk on the disaccharidase activity of newborn rabbit small intestinal mucosal explants were studied in vitro culture. These explants continuously synthesized protein and normal morphology was maintained for the duration of the cultures. Addition of the aqueous phase resulted in significant increase of lactase (p less than 0.001) and maltase (p less than 0.01) concentrations in these organ cultures. This effect was dose dependent and was observed whether the organ biopsies were derived from fed or starved newborn rabbits. Further purification of the aqueous phase showed that the active ingredient exerting these effects was lactose. These studies suggest that lactose may have an important function in stabilization of newborn intestinal disaccharidase enzymes.
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PMID:Effects of the components of breast milk on mucosal enzyme activity of the newborn small intestine. 310 86

Cell-associated oligo-1,6-alpha-glucosidase (EC 3.2.1.10) was isolated from Thermoanaerobium Tok6-B1 grown on starch-containing medium. Activity was purified 11.4-fold by salt precipitation, gel filtration, hydroxyapatite and anion-exchange chromatography. Molecular mass was determined as 30,000 by SDS/polyacrylamide-gel electrophoresis and 33,000 by analytical gel filtration. The probable order of specificity was p-nitrophenyl-alpha D-glucose greater than-isomaltose greater than-isomaltotriose greater than-panose greater than-nigerose and no activity was shown against malto-oligosaccharides, melezitose, melibiose, raffinose, cellobiose, sophorose, gentiobiose, lactose, pullulan, dextran or amylose. The optima for activity and stability were between pH 5.6 and 7.0 and the half-life at pH 6.5 was 1000 min at 70 degrees C and 20 min at 76 degrees C. Activity was stabilized by substrate, Mg2+, Mn2+ and Ca2+, but was destabilized by Zn2+ and EDTA. N-Ethylmaleimide, glucose and 1-O-methyl-alpha D-glucose were inhibitory but 1-O-methyl-beta D-glucose stimulated activity. The activation energy (Ea) was 109 kJ/mol.
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PMID:A cell-associated oligo-1,6-alpha-glucosidase from an extremely thermophilic anaerobic bacterium, Thermoanaerobium Tok6-B1. 321 28

The effect of inhibition of disaccharidases on the degree of absorption of glucose, lactose, and sucrose was examined utilizing an in vivo model in the rat. Acarbose, a competitive alpha-glucosidase inhibitor was utilized to selectively inhibit small intestinal mucosal enzymes. Adult rats (250-350 g body weight) were the subjects of intraduodenal bolus infusion experiments with either sugar alone or sugar plus acarbose. All sugars were infused at a dose of 0.5 g/kg body weight. Portal venous blood glucose was determined at 30-min intervals from 0 to 150 min. Glucose (monosaccharide) and lactose (beta-galactoside) absorption were not altered by the presence of acarbose. In contrast, sucrose (alpha-glucosidase) absorption was significantly diminished in the presence of acarbose. Sucrose absorption in the presence of increasing acarbose doses (0.7-5.6 mg/kg body weight) was depressed in a dose-dependent fashion. Linear regression analysis revealed a high degree of correlation between residual sucrase activity and area under blood glucose curve (r = 0.9837). Similar degrees of correlation were found between acarbose dose and area under blood glucose curve (r = -0.9322), and between residual sucrase activity and acarbose dose (r = -0.9695). These data confirm that acarbose is a selective alpha-glucosidase inhibitor that does not affect monosaccharidase transport. In the presence of acarbose, alpha-glucosidase absorption is diminished in a dose-dependent fashion. Postprandial glucose rise following an alpha-glucosidase meal seems to be determined, in the presence of graded acarbose inhibition, by residual mucosal alpha-glucosidase activity.
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PMID:Effects of graded alpha-glucosidase inhibition on sugar absorption in vivo. 329 64


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