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:3.1.3.9 (glucose-6-phosphatase)
3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of daily intraperitoneal administration of Mn2+(4 mg/kg) was investigated on the metabolism of carbohydrates and certain enzymes involved in the oxidation of glucose in the rat liver and blood at the intervals of 30, 60 and 90 days after exposure. Mn2+ had no effect on the contents of blood reducing sugars and proteins, however the levels of pyruvic and lactic acids were reduced at 60 and 90 days after the metal treatment. The contents of liver glycogen and proteins remained unaffected while pyruvic acid content was decreased in Mn2+ treated rat liver throughout the experimental period. The activities of glycogen phosphorylase and lactate dehydrogenase decreased while that of phosphoglucoisomerase and glucose-6-phosphatase increased in the post mitochondrial supernatant at 60 and 90 days of Mn2+ exposure. The levels of hexokinase decreased and FDP-aldolase and fructose-1, 6-diphosphatase increased throughout the experimental period. The magnitude of alteration was found to be greater with the increase in the duration of Mn2+ treatment. Several of the mitochondrial enzymes in the liver were inhibited in the manganese exposed rats which may be responsible to inhibit the rate of dehydrogenation of Kreb cycle's intermediates along with the linked respiratory chain and eventually oxidation in the rat liver.
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PMID:Effects of manganese on carbohydrate metabolism and mitochondrial enzymes in rats. 713 26

The effect of DL alpha-lipoic acid on the nephrotoxic potential of gentamicin was examined. Intraperitoneal injection of gentamicin (100 mg/kg/day) to rats resulted in decreased activity of the glycolytic enzymes-hexokinase, phosphoglucoisomerase, aldolase and lactate dehydrogenase. The two gluconeogenic enzymes--glucose-6-phosphatase and fructose-1,6-diphosphatase, the transmembrane enzymes namely the Na+, K(+)-ATPase, Ca(2+)-ATPase, Mg(2+)-ATPase and the brushborder enzyme alkaline phosphatase, also showed decreased activities. This decrease in the activities of ATPases and alkaline phosphatase suggests basolateral and brush border membrane damage. Decreased activity of the TCA cycle enzymes isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH), suggests a loss in mitochondrial integrity. These biochemical disturbances were effectively counteracted by lipoic acid administration. Lipoic acid administration by gastric intubation at two different concentrations (10 mg and 25 mg/kg/day) brought about an increase in the activity of the glycolytic enzymes, ATPases and the TCA cycle enzymes. The gluconeogenic enzymes however showed a further decrease in their activities at both the concentrations of lipoic acid administered. These observations shed light on the nephroprotective action of lipoic acid against experimental aminoglycoside toxicity and the protection afforded at 25 mg/kg/day of lipoic acid was noted to be higher than that at 10 mg level.
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PMID:Role of DL alpha-lipoic acid in gentamicin induced nephrotoxicity. 765 73

Glucosamine, a potent inhibitor of glucokinase (hexokinase IV or D), was used to estimate the contribution of this enzyme to glucose phosphorylation in freshly isolated rat hepatocytes and its sensitivity to fructose 6-phosphate in situ. Experiments with radiolabelled glucosamine indicated that this amino sugar, at concentrations of 5 or 40 mM, readily penetrated hepatocytes to reach in 1 min a total (i.e., glucosamine+metabolites) intracellular concentration equal to 0.8-1.2-fold its extracellular concentration. In marked contrast, N-acetylglucosamine barely penetrated the cells. The detritiation of [2-3H]glucose, used to estimate glucose phosphorylation in intact cells, was inhibited by glucosamine much more potently than by N-acetylglucosamine, half-maximal effects being reached at about 2.5 and 30 mM respectively. Extrapolation of the data indicated that about 12% of the detritiation was resistant to glucosamine. Dihydroxyacetone (10 mM), lactate (10 mM) + pyruvate (1 mM), and glucagon (1 microM) increased up to 8-fold the concentration of hexose 6-phosphates (glucose 6-phosphate+fructose 6-phosphate) and, against expectations, modestly decreased the detritiation rate measured in the absence of glucosamine. In the presence of 40 mM glucosamine, these agents increased the detritiation rate, which then positively correlated with the concentration of hexose 6-phosphates. This hexose 6-phosphates-dependent detritiation was sensitive to inhibition by vanadate, and was also catalysed by gel-filtered cell-free extracts, as well as by liver microsomes in the presence of phosphoglucoisomerase; it can be explained by an exchange reaction catalysed by glucose-6-phosphatase. When this exchange reaction is taken into account, it appears that the rate of glucose detritiation attributable to glucokinase decreases when the concentration of hexose 6-phosphates increases. This is in agreement with the known effect of fructose 6-phosphate to potentiate the inhibition of glucokinase by its regulatory protein.
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PMID:Glucosamine-sensitive and -insensitive detritiation of [2-3H]glucose in isolated rat hepatocytes: a study of the contributions of glucokinase and glucose-6-phosphatase. 775 69

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) isolated from Plumbago zeylanica Linn, when administered orally, at a dosage of 4 mg/kg body weight induces tumour regression in 3-methyl-4-dimethyl aminoazobenzene (3MeDAB) induced hepatoma in Wistar male rats. The purpose of this investigation was to identify the changes in the rate of glycolysis and gluconeogenesis in tumour-bearing rats and the effects of treatment with Plumbagin. The levels of certain glycolytic enzymes, namely, hexokinase; phosphoglucoisomerase; and aldolase levels increased (p < 0.001) in hepatoma bearing rats, whereas they decreased in Plumbagin administered rats to near normal levels. Certain gluconeogenic enzymes, namely, glucose-6-phosphatase and fructose-1,6-diphosphatase decreased (p < 0.001) in tumour hosts, whereas Plumbagin administration increased the gluconeogenic enzyme levels in the treated animals. These investigations indicate the molecular basis of the different biological behaviour of 3MeDAB induced hepatoma and the anticarcinogenic property of Plumbagin against hepatoma studied in rats.
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PMID:Effect of Plumbagin on some glucose metabolising enzymes studied in rats in experimental hepatoma. 826 73

The effect of 2-deoxy-D-glucose (2DG) and vitamin E on the alterations in glucose metabolism induced by perchloroethylene (PER) was studied in mice. Oral administration of PER (3 g kg-1 body wt. day-1) in sesame oil for 15 days caused a significant increase in liver weight, degeneration/necrosis of hepatocytes and increase in kidney weight, glomerular nephrosis and degeneration. These changes occurred concurrently with a significant decrease in blood glucose level, elevated activities of hexokinase, aldolase and phosphoglucoisomerase and decreased activity of gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-diphosphatase), indicating the sensitivity of liver and kidney as target tissues in PER toxicity. Evidence is presented that both 2DG (500 mg kg-1 body wt. day-1 i.p.) and vitamin E (400 mg kg-1 body wt. day-1 by oral gavage) during concomitant administration prevented most of the above PER-induced biochemical and pathological alterations. These results suggest that early metabolic and pathological perturbations following exposure of PER in mice can provide the basis for its documented potential for chronic effects like cytotoxicity and may be involved in modulation of carcinogenicity.
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PMID:Perchloroethylene-induced alterations in glucose metabolism and their prevention by 2-deoxy-D-glucose and vitamin E in mice. 885 21

The herbal remedy extended by Semecarpus anacardium nut extract against Aflatoxin B1 mediated hepatocellular carcinoma was established by studies on carbohydrate metabolizing enzymes. Since some definite correlation exists between tumour progression and the activities of glycolytic and gluconeogenic enzymes, assessment of alterations in their activity can be used as successful markers of diagnosis and prognosis. The present work compares the activities of glycolytic and gluconeogenic enzymes in hepatocellular carcinoma bearing rats with drug-treated animals. An overall increase in glycolytic enzymes namely hexokinase, phosphoglucoisomerase, and aldolase with a subsequent reduction in gluconeogenic enzymes, glucose-6-phosphatase and fructose-1,6-biphosphatase was observed in plasma and liver homogenates of hepatocellular carcinoma bearing rats. The administration of Semecarpus anacardium nut extract caused a significant decrease in the activity of glycolytic enzymes and an increase in gluconeogenic enzymes' activities to near normal values in drug-treated animals.
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PMID:Modulating effect of Semecarpus anacardium Linn. nut extract on glucose metabolizing enzymes in aflatoxin B1-induced experimental hepatocellular carcinoma. 936 62

An improved method has been developed for the assay of hexokinase (EC 2.7.1.1) levels in human tissue homogenates. The enzyme is quantitated by the spectrophotometric measurement, at 340 nm, of NADPH formed according to the reaction scheme: [formula: see text] In tissue homogenates a number of enzymes are present which can interfere with the assay by reacting with substrates or products of the assay reactions. In the described procedure hexokinase is assayed directly in homogenates under conditions in which the effect of possible contaminating enzymes (glucose dehydrogenase, EC 1.1.1.47; glucose 6-phosphatase, EC 3.1.3.9; glucose phosphate isomerase, EC 5.3.1.9; 6-phosphogluconate dehydrogenase EC 1.1.1.44; and NADP-reducing enzymes) are eliminated. Precision studies on the assay gave within-day reproducibility of 4.3% (CV) on a tissue having a mean activity of 1.68 U/g of tissue, and day-to-day variability of 15% (CV) for a tissue averaging 1.83 U/g of tissue.
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PMID:An improved assay for hexokinase activity in human tissue homogenates. 976 31

Acrylamide (35 mg kg(-1) body wt, i.p.) and mercuric chloride (1 mg kg(-1)body wt, i.m.) were administered as specific and non-specific toxins, respectively, to induce neurotoxicity in rats for a period of 10 days. Two different concentrations (35 and 70 mg kg(-1) body wt, i.p.) of lipoic acid were given as prophylactic therapy to mitigate the toxic neuropathies. Homogenates of cerebrum, cerebellum and sciatic nerves were used for the determination of the activities of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), neuron-specific enolase (NSE), hexokinase, phosphoglucoisomerase, aldolase and glucose-6-phosphatase. Inhibition of the activities of these glucose-metabolizing enzymes by the neurotoxins emphasizes the reduction in glucose utilization by the neural tissues to impart its normal function. The degree of inhibition of the enzymes varies with both of the toxins. Acrylamide seems to be a specific inhibitor of GAPDH and NSE, whereas the inhibition caused by HgCl(2) on the enzymes was more general. Enhanced activities of the enzymes indicate increased glucose utility on lipoate administration. This result may be due to the detoxifying potency and possibly due to the cofactor vitality of lipoate.
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PMID:Activities of glucose-metabolizing enzymes in experimental neurotoxic models with lipoate as an alleviator. 1054 22

The importance of the glycolytic flux for the success of Biomphalaria-Schistosome sporocyst interaction was acertained in this study. Hexokinase (HK), pyruvate kinase(PK), glucose phosphate isomerase(GPI) and lactate dehydrogenase (LD) as four important glycolytic enzymes were markedly stimulated in trematode infected Biomphalaria alexandrina when measured two weeks post exposure to infection with Schistosoma mansoni miracidia. On the other hand phosphoenolpyruvate carboxy kinase (PEPCK), glucose-6-phosphatase (G6Pase) and fructose 1,6 diphosphatase(FDPase) as three gluconeogenic enzymes were slightly affected which confirm the importance of the glycolytic pathway for schistosome-exposed snails. Effect of LC25 of Solanum nigrum leaves dry powder as plant molluscicide on HK, PK and GPI were tested. Treatment with this plant resulted in a significant inhibition of these three investigated enzymes. LC10 concentrations of S. nigrum reduced considerably the infection rate of B. alexandrina with S. mansoni to be 34% compared to an infection rate of 80% in control, non-treated snails. Longer prepatent period and remarkable decrease in cercarial production was also recorded in snails treated with the sublethal concentrations of the molluscicide. As conclusion, susceptibility of B. alexandrina to infection with the digenetic trematode S. mansoni is correlated to the activity levels of the glycolytic enzymes. Moreover, sublethal and less pollutant concentration of S. nigrum could be recommended to control schistosomiasis by disturbing the intramolluscan environment of the parasite.
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PMID:Susceptibility of Biomphalaria alexandrina to infection with Schistosoma mansoni: correlation with the activity of certain glycolytic enzymes. 1094 15

The purpose of this work was to discriminate between two models for glucose-6-phosphatase: one in which the enzyme has its catalytic site oriented toward the lumen of the endoplasmic reticulum, requiring transporters for glucose-6-phosphate, inorganic phosphate (Pi), and glucose (substrate-transport model), and a second one in which the hydrolysis of glucose-6-phosphate occurs inside the membrane (conformational model). We show that microsomes preloaded with yeast phosphoglucose isomerase catalyzed the detritiation of [2-(3)H]glucose-6-phosphate and that this reaction was inhibited by up to 90% by S3483, a compound known to inhibit glucose-6-phosphate hydrolysis in intact but not in detergent-treated microsomes. These results indicate that glucose-6-phosphate is transported to the lumen of the microsomes in an S3483-sensitive manner. Detritiation by intramicrosomal phosphoglucose isomerase was stimulated twofold by 1 mmol/l vanadate, a phosphatase inhibitor, indicating that glucose-6-phosphatase and the isomerase compete for the same intravesicular pool of glucose-6-phosphate. To investigate the site of release of Pi from glucose-6-phosphate, we incubated microsomes with Pb(2+), which forms an insoluble complex with Pi, preventing its rapid exit from the microsomes. Under these conditions, approximately 80% of the Pi that was formed after 5 min was intramicrosomal, compared with <10% in the absence of Pb(2+). We also show that, when incubated with glucose-6-phosphate and mannitol, glucose-6-phosphatase formed mannitol-1-phosphate and that this nonphysiological product was initially present within the microsomes before being released to the medium. These results indicate that the primary site of product release by glucose-6-phosphatase is the lumen of the endoplasmic reticulum.
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PMID:Novel arguments in favor of the substrate-transport model of glucose-6-phosphatase. 1142 73


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