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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)

Coho salmon (Oncorhynchus kisutch), 8 to 18 months of age, were maintained in culture tanks and were fed three semipurified diets. The diets contained 40% of energy from protein and 11.5%, 23%, or 46% of energy from lipid. The body weight gain and food conversion factors were similar among groups of fish fed the diets in each of the three experiments. Wet weight of mesenteric adipose tissue increased with increased amount of lipid in the diet; however, epaxial muscle lipid content was not influenced by the lipid content of the diet. Several hepatic and adipose tissue lipogenic enzymes (fatty acid synthetase, citrate cleavage enzyme, malic enzyme, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP-isocitrate dehydrogenase) were assayed. These lipogenic enzymes exhibited high activities in liver and relatively low concentration in adipose tissue of the fish. The activities of all the hepatic lipogenic enzymes assayed, except for NADP-isocitrate dehydrogenase, were depressed as the level of lipid in the diet was increased; however, the activities of these enzymes in mesenteric adipose tissue were not influenced by the diets fed. The results of this study indicate that dietary lipid depresses hepatic lipogenic enzyme activities and that the liver may be a more important site for fatty acid synthesis than is adipose tissue in coho salmon.
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PMID:Influence of dietary lipid on lipogenic enzyme activities in coho salmon, Oncorhynchus kisutch (Walbaum). 1 2

Partially purified glucose-6-phosphate dehydrogenase was isolated from small amounts of human erythrocytes (15-20 ml). The Km value for glucose-6-phosphate was 35.0 +/- 3.0 micronM, the Km for NADP was 4.27 +/- 0.3 micronM. The optimal activity of the enzyme was at pH 9.0. Glucose-6-phosphate dehydrogenase, dialyzed in presence of 1-10(-5) M NADP, had critical temperature about 52 degrees within 10 min of incubation; without NADP it was at 45 degrees. The method for isolation and purification of the enzyme was modified.
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PMID:[Kinetic properties of partially purified glucosephosphate dehydrogenase of human erythrocytes]. 1 98

Properties of a new form of glucose-6-phosphate dehydrogenase (G6PD) from erythrocytes, called "Kaluga", are described. The enzyme was isolated from erythrocytes of a patient with chronic non-spherocytic hemolytic anemia; in the blood cells 20% of the G6PD activity was maintained as compared with normal state. The partially purified enzyme was shown to be unstable in electrophoresis, it possessed a biphase type of pH-optima; Km value for NADP was decreased for glucose-6-phosphate Km value was normal. The thermostability of G6PD was normal at 46 within 1 hr.
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PMID:[New variant of glucose-6-phosphate dehydrogenase (G-6-PD "Kaluga") from erythrocytes of a patient with chronic nonspherocytic hemolytic anemia]. 1 21

It is shown that in the presence of NADP in the myocardium extracts glucose-6-phosphate is transformed into fructose-6-phosphate, fructose-1,6-diphosphate and lactate. The intensity of this transformation is close to that when NAD is introduced. The addition of crystalline glucose-6-phosphate dehydrogenase to the extracts is not accompanied by formation of lactate, but reduced NADP accumulates which oxidizes due to introduction of pyruvate or oxalacetate into the medium. This process is reconstructed in the system with pure enzymes (glucose-6-phosphate dehydrogenase, lactate dehydrogenase), that evidences for hydrogen transfer from reduced NADP to pyruvate, or to the oxalacetate without participation of transhydrogenase. The oxidation rate of the reduced coenzymes in the myocardium extracts depends on the medium pH: when pH increases, it lowers for NAD-H and rises for NAD-H. The NAD-H divided by NADP-H rate ratio at pH 7.0 for pyruvate is 11.5 and for oxalacetate is 6.5.
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PMID:[Some mechanisms of carbohydrate metabolism regulation with NADP participation]. 1 29

Partially purified glucose-6-phosphate dehydrogenase (G6PD) was studied in erythrocytes of patients with hereditary hemolytic anemia. Kinetic and electrophoretic properties of G6PD distinctly varied both in patients--homozygotes and in maternal heterozygotes. All the enzymes studied together with the decreased activity possessed the reduced Km value for NADP and G6P. Anomalous enzymes were shown to differ from normal ones by several patterns (pH-dependency, thermostability, % of the substrate analogues utilization, electrophoretic mobility etc). The mutant variant of G6PD was not described earlier. The anomalies variant was called "Kremenchug" to indicate the place of proband origination.
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PMID:[Electrophoretic and kinetic properties of the erythrocyte glucose-6-phosphate dehydrogenase of patients with hemolytic anemia related to a deficit in the activity of that enzyme]. 1 39

Zoogloea ramigera I-16 M was found to contain two stereospecific acetoacetyl CoA reductases; one was NADP+-linked and D(-)-beta-hydroxybutyryl CoA specific and the other was NAD+-linked and L(+)-isomer specific. The NADP+-linked enzyme, purified approximately 150-fold, had a pH optimum for the reduction of acetoacetyl CoA at 8.1, but no definite pH optimum for the oxidation for beta-hydroxybutyryl CoA. The apparent Michaelis constants for acetoacetyl CoA and NADPH were 8.3 and 21 micrometer, respectively. The enzyme was markedly inhibited by acetoacetyl CoA at concentrations higher than 10 micrometer. The incorporation of [1-14C]acetyl CoA into poly-beta-hydroxybutyrate (PHB) by bacterial crude extract (containing beta-ketothiolase, acetoacetyl CoA reductases, enoyl CoA hydratases and PHB synthases) or by a system reconstituted from purified preparations of beta-ketothiolase, acetoacetyl CoA reductase and PHB synthase, was observed only in the presence of NADPH, but not NADH. Among various enzymes involved in PHB metabolism, only the specific activity of glucose 6-phosphate dehydrogenase was elevated 5-fold within 2 h after the addition of glucose to the cells grown in the basal medium. These findings suggest that, in Z. ramigera I-16M, acetoacetyl CoA is directly reduced to D(-)-beta-hydroxybutyryl CoA by the NADP+-dependent reductase, and PHB synthesis is at least partially controled by NADPH availability through glucose 6-phosphate dehydrogenase.
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PMID:An NADP-linked acetoacetyl CoA reductase from Zoogloea ramigera. 2 Aug 66

Aggregation of thrombocytes, caused by ADP, affected the rate of anaerobic breakdown of carbohydrates due to inhibition of the glucose degradation, while the rate of lactate formation was not distinctly altered. Content of NAD was decreased simultaneously with an increase in content of NADP; the activity of glucose-6-phosphate dehydrogenase was distinctly increased but the unaltered activity of 6-phosphogluconate dehydrogenase was observed; content of reduced glutathione was increased 15-fold. The activity of NADP-dependent glutathione reductase was increased under effect of ADP; at the same time, the activity of NAD-dependent glutathione reductase did not depend on the diphosphate effect.
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PMID:[Relationship between glycolysis and pentose cycle intensity and thrombocyte aggregation induced by ADP in man]. 2 84

The contents of adenine nucleotides as well as steady-state concentrations of a number of glycolytic, pentose phosphate-pathway and tricarboxylic acid-cycle intermediates were measured in extracts of livers from normal and phenobarbital-treated rats that were perfused with p-nitroanisole. Metabolites were measured in livers that were freeze-clamped during periods of maximal rates of drug metabolism. Treatment of rats with phenobarbital increased rates of p-nitroanisole O-demethylation approx. fivefold. The concentrations of lactate, xylulose 5-phosphate and ribulose 5-phosphate were increased by phenobarbital treatment, whereas that of fructose 1,6-bisphosphate declined. Perfusion of livers with p-nitroanisole produced significant increases in 6-phosphogluconate and ribulose 5-phosphate in livers from phenobarbital-treated rats, but not in livers from control rats. Treatment of rats with phenobarbital caused [NADP(+)]/[NADPH] to change in the direction of more oxidation, as calculated from measured concentrations of 6-phosphogluconate and ribulose 5-phosphate; however, the [NADP(+)]/[NADPH] ratio calculated from ;malic' enzyme was not changed. Additions of p-nitroanisole produced a reduction of NADP(+) as calculated from 6-phosphogluconate dehydrogenase activity, but did not alter the [NADP(+)]/[NADPH] ratio calculated from substrates assumed to be in equilibrium with ;malic' enzyme. Activities of both glucose 6-phosphate dehydrogenase and ;malic' enzyme were increased by phenobarbital treatment. NAD(+) became more reduced as a result of phenobarbital treatment; however, perfusion of livers with p-nitroanisole did not cause a change in the oxidation-reduction state of this nucleotide. Concentrations of adenine nucleotides in livers were not altered significantly by treatment of rats with phenobarbital; however, a significant decline in the [ATP]/[ADP] ratio occurred during mixed-function oxidation of p-nitroanisole in livers from phenobarbital-treated rats, but not in livers from normal rats. Perfusion of livers with two other substrates for mixed-function oxidation, hexobarbital and aminopyrine, produced an increase in the [NADP(+)]/[NADPH] ratio calculated from ;malic' enzyme. In contrast with livers perfused with p-nitroanisole, there was no significant change in adenine nucleotides in livers exposed to hexobarbital or aminopyrine. Addition of 2,4-dinitrophenol (25mum) to the perfusate containing aminopyrine decreased the [ATP]/[ADP] ratio and tended to prevent the oxidation of NADPH observed with aminopyrine alone. Thus in the presence of an uncoupler of oxidative phosphorylation, NADPH generation may exceed its utilization via mixed-function oxidation.
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PMID:Alterations in nicotinamide and adenine nucleotide systems during mixed-function oxidation of p-nitroanisole in perfused livers from normal and phenobarbital-treated rats. 2 4

Kinetic and electrophoretic properties were studied in 230--300 fold purified preparations of glucose-6-phosphate dehydrogenase (G-6-PD) from red cells of donors and patients with hemolytic anemia induced by G-6-PD deficiency. In abnormal variant of G-6-PD isolated from red cells of a patient with hemolytic anemia which had not before been described in the literature was found. The abnormal variant differs from the normal enzyme by a decreased Michaelis constant for G-6-P and NADP, by increased utilization of substrate-analogues (2-deoxy-G-6-P and deamino NADP in particular), by low heat stability, the character of pH dependence, and by the appearance of one band of G-6-PD activity during electrophoresis in polyacrylamide gel. The isolated abnormal variant of G-6-PD has been called "Kremenchug" according to the origin of the patient.
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PMID:Characteristics of a new abnormal variant of G-6-PD in human red cells. 2 34

The kinetic and molecular properties of cyanobacterial glucose-6-phosphate dehydrogenase, partly purified from Anabaena sp. ATCC 27893, show that it undergoes relatively slow, reversible transitions between different aggregation states which differ in catalytic activity. Sucrose gradient centrifugation and polyacrylamide gel electrophoresis reveal three pincipal forms, with approximate molecular weights of 120 000 (M1), 240 000 (M2) and 345 000 (M3). The relative catalytic activities are: M1 less than M2 less than M3. In concentrated solutions of the enzyme, the equilibrium favors the more active, oligomeric forms. Dilution in the absence of effectors shifts the equilibrium in favor of the M1 form, with a marked diminution of catalytic activity. This transition is prevented by a substrate, glucose-6-phosphate, and also by glutamine. The other substrate, nicotinamide adenine dinucleotide phosphate (NADP+), and (in crude cell-free extracts) ribulose-1,5-diphosphate are negative effectors, which tend to maintain the enzyme in the M1 form. The equilibrium state between different forms of the enzyme is also strongly dependent on hydrogen ion concentration. Although the optimal pH for catalytic activity is 7.4, dissociation to the hypoactive M1 form is favored at pH values above 7; a pH of 6.5 is optimal for maintenance of the enzyme in the active state. Reduced nicotamide adenine dinucleotide phosphate (NADPH) and adenosine 5'-triphosphate (ATP), inhibit catalytic activity, but do not significantly affect the equilibrium state. The relevance of these findings to the regulation of enzyme activity in vivo is discussed.
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PMID:Glucose-6-phosphate dehydrogenase of Anabaena sp. Kinetic and molecular properties. 2 37


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