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)

Two mutants carrying different deletions of the IMP2 coding sequence of Saccharomyces cerevisiae, delta T1, which encodes a protein lacking the last 26 C-terminal amino acids, and delta T2, which completely lacks the coding region, were analysed for derepression of glucose-repressible maltose, galactose, raffinose and ethanol utilization pathways in response to glucose limitation. The role of the IMP2 gene product in the regulation of carbon catabolite repressible enzymes maltase, invertase, alcohol dehydrogenase, NAD-dependent glutamate dehydrogenase (NAD-GDH) and L-lactate:ferricytochrome-c oxidoreductase (L-LCR) was also analysed. The IMP2 gene product is required for the rapid glucose derepression of all above-mentioned carbon source utilization pathways and of all the enzymes except for L-LCR. NAD-GDH is regulated by IMP2 in the opposite way and, in fact, this enzyme was released at higher levels in both imp2 mutants than in the wild-type strain. Therefore, the product of IMP2 appears to be involved in positive and negative regulation. Both deletions result in growth and catalytic defects; in some cases partial modification of the gene product yielded more dramatic effects than its complete absence. Moreover, evidence is provided that the IMP2 gene product regulates galactose- and maltose-inducible genes at the transcriptional level and is a positive regulator of maltase, maltose permease and galactose permease gene expression.
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PMID:IMP2, a gene involved in the expression of glucose-repressible genes in Saccharomyces cerevisiae. 749 32

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

The expression of gluconeogenic fructose-1,6-bisphosphatase (encoded by the FBP1 gene) depends on the carbon source. Analysis of the FBP1 promoter revealed two upstream activating elements, UAS1FBP1 and UAS2FBP1, which confer carbon source-dependent regulation on a heterologous reporter gene. On glucose media neither element was activated, whereas after transfer to ethanol a 100-fold derepression was observed. This gene activation depended on the previously identified derepression genes CAT1 (SNF1) (encoding a protein kinase) and CAT3 (SNF4) (probably encoding a subunit of Cat1p [Snf1p]). Screening for mutations specifically involved in UAS1FBP1 derepression revealed the new recessive derepression mutation cat8. The cat8 mutants also failed to derepress UAS2FBP1, and these mutants were unable to grow on nonfermentable carbon sources. The CAT8 gene encodes a zinc cluster protein related to Saccharomyces cerevisiae Gal4p. Deletion of CAT8 caused a defect in glucose derepression which affected all key gluconeogenic enzymes. Derepression of glucose-repressible invertase and maltase was still normally regulated. A CAT8-lacZ promoter fusion revealed that the CAT8 gene itself is repressed by Cat4p (Mig1p). These results suggest that gluconeogenic genes are derepressed upon binding of Cat8p, whose synthesis depends on the release of Cat4p (Mig1p) from the CAT8 promoter. However, gluconeogenic promoters are still glucose repressed in cat4 mutants, which indicates that in addition to its transcription, the Cat8p protein needs further activation. The observation that multicopy expression of CAT8 reverses the inability of cat1 and cat3 mutants to grow on ethanol indicates that Cat8p might be the substrate of the Cat1p/Cat3p protein kinase.
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PMID:CAT8, a new zinc cluster-encoding gene necessary for derepression of gluconeogenic enzymes in the yeast Saccharomyces cerevisiae. 789 85

Maternal ingestion of alcohol is believed to be one factor that greatly influences the development of intrauterine growth retardation (IUGR) and postnatal growth failure. The present study was undertaken to determine whether maternally ingested alcohol adversely affects fetal growth and intestinal mucosal function. Five time-mated New Zealand white rabbit does were given ethanol intravenously (ETH group) (30% vol/vol; 1.0 g/kg/d) on gestational days (GD) 15 through 29 (term, 31 days). Two other rabbits received the same dose of ethanol. Maternal, fetal, and amniotic fluid alcohol levels were measured on GD 24. Four control rabbits (SH group) received normal saline (25 mL, intravenously). At term, the animals were delivered by cesarean section and killed. Seventeen of the 42 ETH fetuses survived the study period (43%); all 24 SH fetuses survived. On GD 24, within 60 minutes after maternal ethanol infusion, the fetal blood alcohol concentration (BAC) increased to 153 +/- 1.97 mg/dL (v maternal, 179 +/- 1.75 mg/dL); the amniotic ethanol level increased to 46 +/- 1.32 mg/dL. Birth weight was lower in the ETH group (46.88 +/- 2.21 g) than in the SH group (55.78 +/- 1.80 g) (P < .01). Disaccharidase activity, an indicator of intestinal mucosal function, showed that lactase activity (per milligram of protein) was significantly lower in ETH fetuses (2.60 x 10(-2) +/- 0.22 UE/mg) than in SH fetuses (3.50 x 10(-2) +/- 0.25 UE/mg) (P = .01); maltase activity and protein content were not affected significantly. This report provides the first description of the adverse effects of maternal alcohol ingestion on the small intestinal mucosal function of the fetal rabbit.
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PMID:Effect of maternal ethanol intake on fetal rabbit gastrointestinal development. 796 1

Cells of the fission yeast Schizosaccharomyces pombe were permeabilized by treatment with toluene-ethanol. The permeabilized cells lost the bulk of the internal trehalose pool while most of the alkaline phosphatase, invertase, alpha-glucosidase, or neutral trehalase activities located inside the cells remained unaffected. This system was used as an in situ assay to determine the involvement of trehalose in enzyme protection during thermal treatments. The addition of trehalose to suspensions of permeabilized cells resulted in a sugar-dependent thermoprotection of the internal marker enzymes. This approach demonstrates that in whole cells of the fission yeast trehalose plays a physiological role as a protective molecule against thermal denaturation of cellular enzymes.
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PMID:Increased thermal stability of the enzyme content in permeabilized whole cells from the fission yeast Schizosaccharomyces pombe by exogenous trehalose and other compounds. 859 Apr 7

Ethanol consumption has a toxic effect on the epithelium of the small bowel, but enterocyte maturity is very difficult to measure under these circumstances. However, when ethanol intake is combined with enterectomy, enterocyte immaturity is greater, permitting an easier separation of these two effects. In a group of rats (13 male Wistar rats weighing approximately 220 g) fed a liquid diet containing 35% ethanol for 4 weeks after resection of the proximal jejunum, the residual small intestine brush border maltase, sucrase, and lactase activities were similar to those of a pair-fed control group (13 animals). However, alkaline phosphatase activity was decreased in the mucosa and in the enterocyte brush border, probably because of the lower activity of this enzyme in the jejunum-ileum remnant of the alcoholic group.
Alcohol Clin Exp Res 1996 Feb
PMID:Effect of chronic ethanol consumption on the activities of residual small bowel brush-border enzymes after proximal jejunum resection in the rat. 865 45

Brush border enzymatic activities (maltase, lactase and sucrase) have been determined in the ileal mucosa of rats subjected to a 30% ethanol ingestion for 3 and 5 months. The data were compared with the results obtained with control rats. Mucosal protein content after 3 months of ethanol treatment was similar to that of control rats. Maltase, lactase and sucrase specific activities in ileal mucosa were significantly decreased in ethanol-fed animals as compared to control rats. After 5 months of ethanol consumption, the protein content was decreased in ethanol-fed rats. However, no differences were found between specific activities of maltase, lactase and sucrase of ethanol-fed with respect to control rats. It is suggested that prolonged exposure of rats to ethanol results in adaptive responses to the effects of shorter periods of exposure on intestinal mucosal function.
Alcohol Alcohol 1996 Jan
PMID:Changes in the ileal disaccharidase activities in rats after long-term ethanol feeding. 867 76

Glucose homeostasis is maintained by a balance between the release and action of insulin, and the counterregulatory responses mediated principally by glucagon, catecholamines, growth hormone and cortisol. Hence, the effects of a drug on glucose metabolism may be mediated by any of these agents singly or in combination. Host factors, such as inherent glucoregulatory mechanisms, concurrent diseases, organ function and concomitant medications also increase the risk of drug-induced disturbances of glucose homeostasis in susceptible individuals. By far the most important agents causing hypoglycaemia are insulin and the sulphonylureas. Alcohol (ethanol), over-zealous glycaemic control, hypoglycaemic unawareness, detective counterregulation especially in insulin-dependent diabetes mellitus (IDDM), and renal and liver impairment are all important predisposing factors. Although antihyperglycaemic agents such as metformin and alpha-glucosidase inhibitors do not cause hypoglycaemia alone, they may enhance the hypoglycaemic effects of potent hypoglycaemic agents such as insulin and sulphonylureas. On the other hand, the potential hypoglycaemic effects of ACE inhibitors, alpha-blockers, lipid-lowering agents and recombinant human insulin-like growth factor demonstrated in experimental settings, are of potential therapeutic interest. Iatrogenic hypoglycaemia and intensive insulin treatment are associated with hypoglycaemic unawareness which may be obviated by meticulous avoidance of hypoglycaemia. Effective patient education remains an important preventive measure. Oral glucose is used to treat mild hypoglycaemic episodes while more severe episodes are treated by intravenous glucose or glucagon. Nasal glucagon and theophylline are other experimental measures to improve recovery from hypoglycaemia. In refractory hypoglycaemia due to hyperinsulinaemia such as during sulphonylurea overdosage or quinine treatment, the long-acting somatostatin, octreotide, may suppress insulin release and restore euglycaemia. Diuretics, beta-blockers, sympathomimetics, corticosteroids and sex hormones are commonly prescribed drugs which may have adverse effects on carbohydrate metabolism especially in patients with diabetes mellitus or those who are at risk of developing glucose intolerance. Pentamidine was frequently associated with dysglycaemia due to its pancreatic beta-cell cytotoxic effects but is now used less often to treat Pneumocystis carinii pneumonia in immunosuppressed patients. Despite the large number of anecdotal reports of drug-induced disturbances of glucose metabolism, many of the so-called adverse drug reactions were either idiosyncratic or coincidental. Nevertheless, they emphasise the complex nature of glucose homeostasis and its potential interactions with drugs, host factors and disease states. An understanding of these relationships may allow more critical interpretation of these clinical observations, better prediction of drug induced adverse effects on carbohydrate metabolism and the implementation of more rational therapy. Hence, the hypoglycaemic effects of a drug may be turned to a therapeutic advantage in patients with glucose intolerance. Similarly, the hyperglycaemic effect of a drug may help to treat refractory hypoglycaemia.
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PMID:Drug-induced disorders of glucose metabolism. Mechanisms and management. 888 64

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

The treatment of Caco-2 cells, a human colon adenocarcinoma cell line that closely resembles normal human small intestinal epithelial cells, with acetaldehyde resulted in significantly decreased activities of brush border enzymes sucrase, maltase, lactase, and gamma-glutamyltransferase; alkaline phosphatase activity was not affected. In the case of sucrase and maltase, the activities were also decreased by a combination of acetaldehyde and ethanol, although ethanol alone markedly increased them. The possibility that intraintestinal acetaldehyde, formed by intestinal microbes, might play a role in some small intestinal enzyme deficiencies observed earlier in alcoholics should therefore be considered. The mechanism by which acetaldehyde alters these enzyme activities remains unclear. The observation that acetaldehyde also disturbed cell polarization, an initial step in the process of differentiation in Caco-2 cells, indicates that acetaldehyde might decrease these enzyme activities by interfering with cell differentiation. Because ethanol and acetaldehyde metabolizing enzymes have not been previously studied from Caco-2 cells, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities were also measured from these cells, and their ALDH isoenzyme pattern was characterized. Like many cancerous cell lines, Caco-2 cells were found to express no ADH. They, however, possessed ALDH activity that was comparable with normal colonic mucosal activity and also expressed the same ALDH classes (ALDHs 1 to 3) than normal human colonic mucosa.
Alcohol Clin Exp Res 1997 Dec
PMID:Effects of acetaldehyde on brush border enzyme activities in human colon adenocarcinoma cell line Caco-2. 943 18


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