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)

Clostridium thermosulfurogenes displayed faster growth on either glucose, maltose, or starch than Clostridium thermohydrosulfuricum. Both species grew faster on glucose than on starch or maltose. The fermentation end product ratios were altered based on higher ethanol and lactate yields on starch than on glucose. In C. thermohydrosulfuricum, glucoamylase, pullulanase, and maltase were mainly responsible for conversion of starch and maltose into glucose, which was accumulated by a putative glucose permease. In C. thermosulfurogenes, beta-amylase was primarily responsible for degradation of starch to maltose, which was accumulated by a putative maltose permease and then hydrolyzed by glucoamylase. Regardless of the growth substrate, the rates of glucose, maltose, and starch transformation were higher in C. thermosulfurogenes than in C. thermohydrosulfuricum. Both species had a functional Embden-Meyerhof glycolytic pathway and displayed the following catabolic activities: ferredoxin-linked pyruvate dehydrogenase, acetate kinase, NAD(P)-ethanol dehydrogenase, NAD(P)-ferredoxin oxidoreductase, hydrogenase, and fructose-1,6-diphosphate-activated lactate dehydrogenase. Ferredoxin-NAD reductase activity was higher in C. thermohydrosulfuricum than NADH-ferredoxin oxidase activity, but the former activity was not detectable in C. thermosulfurogenes. Both NAD- and NADP-linked ethanol dehydrogenases were unidirectional in C. thermosulfurogenes but reversible in C. thermohydrosulfuricum. The ratio of hydrogen-producing hydrogenase to hydrogen-consuming hydrogenase was higher in C. thermosulfurogenes. Two biochemical models are proposed to explain the differential saccharide metabolism on the basis of species enzyme differences in relation to specific growth substrates.
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PMID:Differential amylosaccharide metabolism of Clostridium thermosulfurogenes and Clostridium thermohydrosulfuricum. 393 39

Screening in batch cultures identified Debaryomyces yamadae as a yeast that exhibits the Kluyver effect for sucrose: this disaccharide can be respired but, even under oxygen-limited conditions, alcoholic fermentation of sucrose does not occur. Ethanol, glycerol and arabitol were the main fermentation products during oxygen-limited growth on glucose in chemostat cultures. None of these fermentation products were produced in oxygen-limited chemostat cultures grown on sucrose and the fraction of the sucrose that could not be respired remained unused in the culture medium. This absence of alcoholic fermentation was not due to repression of the key fermentative enzymes pyruvate decarboxylase and alcohol dehydrogenase. In contrast to some other yeasts that exhibit a Kluyver effect, D. yamadae did not exhibit a preference for ethanol in batch cultures grown on mixtures of ethanol and sucrose. Sucrose metabolism in D. yamadae involves intracellular hydrolysis by an alpha-glucosidase. Incubation of weakly buffered cell suspensions with sucrose led to a rapid transient alkalinization, indicating the presence of a sucrose-proton symport system. The apparent substrate saturation constant of the sucrose-uptake system was 0.2 mmol l-1. Sucrose-dependent alkalinization rates were much lower in samples from oxygen-limited cultures than in samples from aerobic cultures. Transient responses of D. yamadae to oxygen limitation were investigated by applying a sudden decrease in the oxygen feed to aerobic sugar-limited chemostat cultures. In glucose-grown cultures, this led to alcoholic fermentation and no significant accumulation of sugar occurred after the switch. In sucrose-limited cultures, sugar accumulation occurred instantaneously after the switch, and ethanol formation was virtually absent.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Coordination of sucrose uptake and respiration in the yeast Debaryomyces yamadae. 755 Oct 25

Summary. Many studies have shown that experimental type 1 diabetes causes morphological, functional, and metabolic alterations in the small intestine. The more frequent form of the disease, type 2 diabetes, however, has been less studied. Here the influence of diabetes on the functionality of the small intestine was studied in an experimental diabetes model, with a certain degree of residual insulin secretion, specifically in the n0-STZ model. - The diabetic rats in this model were found to have glycaemia levels higher than in the controls (8.82 +/- 0.27 and 6.18 +/- 0.18 mmol/L; p < 0.01), while their plasma insulin levels were lower than in the control rats (2.65 +/- 0.32 and 3.60 +/- 0.25 ng/ml; p < 0.05). Although there were no significant variations in body weight between the two groups, both the weight and the length of the intestine were significantly greater (p < 0.05) in the diabetic rats than in the controls. The sucrase and maltase activities were greater (p < 0.01) in the proximal intestine of the diabetic rats (94 +/- 8 and 234 +/- 12 mU/mg protein, respectively) than in the control rats (50 +/- 2 and 149 +/- 20 mU/mg protein, respectively). The 6-phosphofructo-1-kinase activity (mU/mg proteins) was less (p < 0.05) in the proximal and distal intestine of the diabetic rats (160 +/- 40 and 80 +/- 20, respectively) than in the controls (280 +/- 30 and 230 +/- 30, respectively). No significant differences were observed in the lactate dehydrogenase or active and total pyruvate dehydrogenase measured in the distal and proximal intestine of control and diabetic rats. In conclusion, our results show that experimental diabetes (n0-STZ model) similar to human type 2 diabetes produces certain morphological and enzymatic alterations which affect the digestion and absorption of carbohydrates and the intestinal metabolism of glucose. These alterations may contribute to producing the post-prandial hyperglycaemia which characterizes diabetes.
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PMID:Morphological and enzymatic changes of the small intestine in an n0-STZ diabetes rat model. 1201 71

Short-chain fructooligosaccharides (scFOS) and other prebiotics are used to selectively stimulate the growth and activity of lactobacilli and bifidobacteria in the colon. However, there is little information on the mechanisms whereby prebiotics exert their specific effects upon such microorganisms. To study the genomic basis of scFOS metabolism in Lactobacillus plantarum WCFS1, two-color microarrays were used to screen for differentially expressed genes when grown on scFOS compared to glucose (control). A significant up-regulation (8- to 60-fold) was observed with a set of only five genes located in a single locus and predicted to encode a sucrose phosphoenolpyruvate transport system (PTS), a beta-fructofuranosidase, a fructokinase, an alpha-glucosidase, and a sucrose operon repressor. Several other genes were slightly overexpressed, including pyruvate dehydrogenase. For the latter, no detectable activity in L. plantarum under various growth conditions has been previously reported. A mannose-PTS likely to encode glucose uptake was 50-fold down-regulated as well as, to a lower extent, other PTSs. Chemical analysis of the different moieties of scFOS that were depleted in the growth medium revealed that the trisaccharide 1-kestose present in scFOS was preferentially utilized, in comparison with the tetrasaccharide nystose and the pentasaccharide fructofuranosylnystose. The main end products of scFOS fermentation were lactate and acetate. This is the first example in lactobacilli of the association of a sucrose PTS and a beta-fructofuranosidase that could be used for scFOS degradation.
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PMID:Identification of prebiotic fructooligosaccharide metabolism in Lactobacillus plantarum WCFS1 through microarrays. 1726 21