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Query: EC:1.1.1.49 (glucose-6-phosphate dehydrogenase)
 7,794 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glucose-adapted Streptococcus faecalis produced little if any (14)CO(2) from glucose-1-(14)C, although high levels of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) were detected in cell-free extracts. Metabolism of glucose through the oxidative portion of the hexose-monophosphate pathway was shown to be regulated in this organism by the specific inhibitory interaction of the Embden-Meyerhof intermediate, fructose-1, 6-diphosphate (FDP), with 6-phosphogluconate dehydrogenase. Glucose-6-phosphate dehydrogenase activity was unaffected by FDP. The S. faecalis 6-phosphogluconate dehydrogenase was partially purified from crude extracts by standard fractionation procedures and certain kinetic parameters of the FDP-mediated inhibition were investigated. The negative effector was shown to cause a decrease in V(max) and an increase in the apparent K(m) for both 6-phosphogluconate and nicotinamide adenine dinucleotide phosphate (NADP). These effects were apparently a consequence of the ligand interacting with the enzyme at a site distinct from either the substrate or the coenzyme sites. Among the evidence supporting this was the fact that beta-mercaptoethanol blocked completely FDP inhibition, but had no effect on catalytic activity. The possibility that the regulation of 6-phosphogluconate dehydrogenase activity by FDP might be of some general significance was suggested by the observation that this enzyme from several other sources was also sensitive to FDP.
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PMID:Mechanism for regulating the distribution of glucose carbon between the Embden-Meyerhof and hexose-monophosphate pathways in Streptococcus faecalis. 439 92

Glucose-6-phosphate dehydrogenase was partially purified from both glucose-grown and iron-glucose-grown Thiobacillus ferrooxidans. The enzyme possesses a dual nucleotide specificity for either nicotinamide adenine dinucleotide phosphate (NADP) or nicotinamide adenine dinucleotide (NAD) and has a molecular weight of 110,000 as determined by gel electrophoresis. Evidence is presented that T. ferrooxidans glucose-6-phosphate dehydrogenase is identical when isolated from cells grown mixotrophically (iron-glucose grown) or cells grown heterotrophically (glucose-grown cells). The enzyme is activated by Mg(2+), and to a lesser extent by low concentrations of Mn(2+). Reduced NAD inhibits the enzyme from T. ferrooxidans. No deviation from normal Michaelis-Menten kinetics was observed in velocity versus substrate concentration experiments. Adenosine triphosphate exerted a profound inhibition of the enzyme; the effect was 10 times more pronounced in the presence of NAD as compared to NADP. The physiological significance of this inhibition is discussed.
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PMID:Glucose-6-phosphate dehydrogenase from the chemolithotroph Thiobacillus ferrooxidans. 439 40

Glucose-6-phosphate dehydrogenase specific to the erythrocytes of each of two wild hares found in Europe was discerned by starch-gel electrophoresis at pH 7.0 and pH 8.6. The single, sharp band of the dehydrogenase of Lepus europaeus was faster than that of L. timidus, at both pH levels. The sex-linkage of this enzyme was tested through reciprocal hybrids between the two species. Each male hybrid had a single band of enzyme identical with that of its mother, while both parental types of this enzyme coexisted in female hybrids. Thus, sex-linkage of glucose-6-phosphate dehydrogenase has been suggested not only in man and in the family Equidae, but now in the family Leporidae of placental mammals as well.
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PMID:Sex-linkage of erythrocyte glucose-6-phosphate dehydrogenase in two species of wild hares. 585 29

The hormonal regulation of two regulatory enzymes of fatty acid synthesis acetyl-CoA carboxylase (EC 6.4.1.2) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49), has been investigated in human diploid fibroblasts. There was a 35% increase in acetyl-CoA carboxylase activity, 72 h following addition of 10 microU/ml insulin to the culture medium. Addition of 1 microgram/ml of 3,3'5-triiodothyronine for 72 h resulted in an increase in acetyl-CoA carboxylase activity to 166% of the controls. The simultaneous addition of 1 microgram/ml triiodothyronine and 10 mU/ml insulin caused the enzyme activity to rise to 240% of the controls. A dose-dependent reduction in acetyl-CoA carboxylase activity was brought about by 1 X 10(-4) to 1 X 10(-3) M dibutyryl cyclic AMP. The earliest effect of dibutyryl cyclic AMP was observed within 24 h. Glucose-6-phosphate dehydrogenase followed qualitatively the same pattern of response, whereas the constitutive enzyme, lactate dehydrogenase (EC 1.1.1.27), did not show significant changes in these experiments. The data demonstrate common features of hormonal regulation of lipogenesis in human fibroblasts with liver and adipose tissue and substantiate the growing evidence that thyroid hormones are of major importance for the regulation of this process.
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PMID:Regulation of lipogenic enzymes in human diploid fibroblasts by hormones. 613 Jul 94

The liver lipogenic enzymes are compared among rats, chickens, frogs and fish. Although the apparent Km values of glucose-6-phosphate dehydrogenase for glucose-6-phosphate are not much different among all the species, those of malic enzyme for malate are much higher in chickens and fish than in rats and frogs. Glucose-6-phosphate dehydrogenase showed very high activities compared with malic enzyme in fish liver, and malic enzyme showed high activities in chicken liver. Although the apparent Km values of acetyl-CoA carboxylase and fatty acid synthetase for substrates are in the same range among all the animals, the activity of acetyl-CoA carboxylase seems to be extremely low in fish and frog livers, and that of fatty acid synthetase is low in frog livers only. In addition, the apparent Km values of alpha-glycerophosphate acyltransferase of fish liver are very high, and the enzyme activity appears to be extremely low compared to the others. Therefore, the enzymes at the first steps of both fatty acid and glycerolipid syntheses of poikilothermos animals appear to be very low. On the other hand, the Ouchterlony double-diffusion patterns showed that the lipogenic enzymes of chickens, frogs and fish are immunologically different from those of rats, with the exception of acetyl-CoA carboxylase in chickens. Therefore, it is suggested that the fatty acid and glycerolipid forming systems of poikilothermos animals are quite different from those of homoiothermos and the lipogenesis is very low in poikilothermos.
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PMID:Comparative study of lipogenic enzymes in several vertebrates. 615 20

A histochemical study of the metabolism of rat renal arteries and arterioles. Rat renal arteries and arterioles were examined histochemically to determine their metabolic profiles. Succinate, malate and NAD-isocitrate dehydrogenase, cytochrome oxidase and ubiquinone were assessed to determine aerobic metabolism. Glucose-6-phosphate dehydrogenase and DPN diaphorase were evaluated to determine hexose-monophosphate-shunt activity. Anaerobic metabolism was evaluated via lactate dehydrogenase, and the substrate, glycogen. Gomori's lipase, beta-hydroxybutyrate dehydrogenase and amounts of neutral fat and free fatty acids were assessed as indicators of lipid utilization. Myosin ATPase activity was evaluated as an index of ATP utilization for contraction. Deoxyribonucleic and ribonucleic acids were appraised as indicators of protein synthesis. In general, the oxidative enzymes and myosin ATPase demonstrate considerable activity in renal arteries and arterioles which suggests aerobic metabolism and ATP usage. Renal arteries and arterioles also appear capable of anaerobic metabolism as indicated by strong lactate dehydrogenase reactivity and by the presence of slight to moderate quantities of glycogen, while high levels of glucose-6-phosphate dehydrogenase and moderate amounts of deoxyribonucleic acid suggest a potential for beta-hydroxybutyrate dehydrogenase, minimal lipase activity, and the absence of fatty acids with substantial amounts of neutral fat, indicate limited lipid catabolism.
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PMID:A histochemical study of the metabolism of rat renal arteries and arterioles. 620 11

Glucose-6-phosphate dehydrogenase activity was significantly lower in adipose tissue of human subjects after 7 days of severe caloric restriction on low-carbohydrate diets and had returned to normal values 4 days after the subjects resumed normal diets. Three other enzyme activities (malate-NADP dehydrogenase, oxaloacetate decarboxylating; ATP-citrate lyase and 6-phosphofructokinase) were not significantly affected by these dietary changes. These results are consistent with separate control of glucose-6-phosphate dehydrogenase activity versus other 'lipogenic' enzyme activities in human adipose tissue.
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PMID:Regulation of glucose-6-phosphate dehydrogenase activity during caloric restriction in human adipose tissue. 621 92

After incubation of rabbit red blood cells with 10 micrograms/ml of cortisol, a decrease of the activity of glucose-6-phosphate dehydrogenase, phosphofructokinase and acid phosphatase was observed. Glucose-6-phosphate dehydrogenase and phosphofructokinase were isolated from hemolysate and investigated. No changes in the affinity of both enzymes towards substrates and coenzymes were found. Cortisol modified allosteric properties of phosphofructokinase. Differences were seen between the erythrocyte and reticulocyte enzyme. In the erythrocyte enzyme the inhibitory effect of ATP and citrate was enhanced and the activatory effect of AMP was abolished after incubation with cortisol. Cortisol showed no effect on the inhibition of reticulocyte phosphofructokinase by ATP or activation by AMP, and protected the enzyme toward inhibition by citrate.
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PMID:Effect of cortisol on erythrocyte and reticulocyte enzymes: modulation of phosphofructokinase properties. 622 5

In diabetic rats transplanted with fetal pancreata we measured the activities of six important enzymes to assess the return of liver metabolism to normal. Comparison was made among the responses of transplanted rats with and without renal-portal vein shunts and of those not transplanted and injected with insulin in varying doses. Insulin supply was not limited since three or four fetal pancreata were first grown in normal rats before transfer into the diabetic animals. Transplantation normalized blood and urine glucose and the rate of disappearance of intravenous glucose. Glucokinase and pyruvate kinase activities in liver rose toward normal at 7 days after transplantation and reached normal levels at 30 and 90 days. The response of the other four enzymes, glucose-6-phosphate dehydrogenase, citric lyase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase, was more rapidly restored to normal at 7 days and remained normal at 30 and 90 days. No difference was observed in the enzyme activities of transplanted-shunted rats to nonshunted animals. Glucokinase activity was restored to normal after 1 wk of daily injections of 1 U of PZI; pyruvate kinase restoration required 3 U/day. Glucose-6-phosphate dehydrogenase and citric lyase required 2 U/day to be restored to normal; 3 U daily resulted in temporary supernormal activities. The gluconeogenic enzymes, fructose-1,6-bisphosphatase and glucose-6-phosphatase, were only partially suppressed toward normal by insulin even with 3 U daily for 3 wk. These findings indicate that pancreas transplantation is a more effective regulator of liver metabolism in diabetes than insulin injections.
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PMID:Normalization of six key hepatic enzymes after fetal pancreas transplantation in diabetic rats. 630 89

Glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49)-deficient red blood cells from male hemizygotes and female heterozygotes from the island of Sardinia were studied for their ability to support growth in vitro of the malaria-causing organism Plasmodium falciparum. Parasite growth was approximately one-third of normal in both hemi- and heterozygotes for G6PD deficiency. In Sardinians with the beta 0-thalassemia trait, parasite growth was normal except when G6PD deficiency occurred together with the thalassemia trait. The data support the hypothesis that G6PD deficiency may confer a selective advantage in a malarious area; the female heterozygote may be at a particular advantage because resistance to malaria equals that of male hemizygotes, but the risk of fatal hemolysis may be less. However, more female heterozygotes must be studied to confirm this hypothesis. No protective effect of beta 0-thalassemia trait could be demonstrated in vitro.
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PMID:Glucose-6-phosphate dehydrogenase deficiency inhibits in vitro growth of Plasmodium falciparum. 633 74


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