Specific activities of 6-phosphogluconate dehydrogenase,glucose-6-phosphate dehydrogenase and glucose-6-phosphate isomerase during Bufo bufo development

It has been suggested by some authors that during amphibian development, due to the higher glucose-6-phosphate dehydrogenase (EC 1.1.1.49) activity compared to that of 6-phosphogluconate dehydrogenase (EC 1.1.1.43), 6-phosphogluconate could accumulate in the embryo tissues and regulate the channelling of glucose-6-phosphate into glycolysis. Here, on the base of the specific activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate isomerase (EC 5.3.1.9) found in the embryos of Bufo bufo during development, it is discussed whether 6-phosphogluconate can accumulate and play a regulative role on glucose-6-phosphate metabolism in the anuran embryo.     

Effectors of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase of rat liver.

Summary The lower Vmax of 6PGDH with respect to G6PDH and its higher sensitivity to inhibition by NADPH, suggest the existence of an imbalance between the two dehydrogenases of the pentose phosphate pathway in rat liver. Possible modulators of these activities, particularly in relation with the inhibition by NADPH in physiological conditions, have been investigated. The results suggest that in both cases the inhibition by NADPH is strictly isosteric and that the relative affinities for the reduced and oxidized forms of the pyridine nucleotide are unaffected by glutathion, the intermediates of the pentose phosphate shunt or some divalent ions.Abbreviations G6PDH glucose-6-phosphate dehydrogenase (EC 1.1.1.49) - 6PGDH 6-phosphogluconate dehydrogenase (EC 1.1.1.44) On leave from the Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.     

Association of red cell glucose-6-phosphate dehydrogenase with haemoglobinopathies

A total of 1,112 randomly selected Saudi Arabs, of both sexes, living in Jeddah and the surrounding areas were screened for the phenotypic distribution of red cell glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD). They were also investigated for haemoglobin and for thalassaemia. Phenotyping of the haemoglobins and the red cell enzymes was carried out by starch gel electrophoresis and the dye-decolouration screening test, while the investigation for thalassaemia was carried out by globin-chain biosynthesis, followed by column chromatography. The red cell Gd- alleles were significantly associated with the sickle-cell gene in both the males (chi 2(1): AS-28.80; SS-4.89) and females (chi 2(1): AS-10.99; SS-13.16). A similar association was also observed between G6PD deficiency and thalassaemias in males (chi 2(1): alpha-thalassaemia - 3.13; beta-thalassaemia - 11.06) and females (chi 2(1): alpha-thalassaemia - 6.63). However, no such association was detected between red cell 6PGD types and haemoglobin genes. The results suggest that the red cell G6PD deficiency, sickle-cell and thalassaemia genes might have evolved as a result of the same ecological factor, probably malaria.     

Two isoenzymes each of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in spinach leaves

Isoenzymes of glucose-6-phosphate dehydrogenase and 6-P-gluconate dehydrogenase from a 70% ammonium sulfate precipitate of spinach leaf homogenate were separated by differential solubilization in a gradient of 70-0% ammonium sulfate and analyzed by disc gel electrophoresis. Isolated whole chloroplasts contained isoenzyme 1 of both glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase 1, whereas isoenzyme 2 of each was found in the soluble cytosol fraction. Both isoenzymes of each dehydrogenase were present in about equal amounts. Glucose-6-phosphate dehydrogenase isoenzymes 1 and 2 had pH optima of 9.2 and 9.0 and K_m values of 400 and 330 μm, respectively. Molecular weights for both isoenzyme of glucose-6-phosphate dehydrogenase were very similar at about 105,000 ± 10% as estimated by sedimentation velocity measurements. For 6-phosphogluconate dehydrogenase isoenzymes 1 and 2 the pH optima were 9.0 and 9.3, respectively, the K_m values were 100 and 80 μm, and the apparent molecular weights were also nearly identical at about 110,000 ± 10%. The data support the hypothesis that leaf cells have two oxidative pentose phosphate pathways, one in the chloroplast and the other in the cytosol.     

Regulation of specific activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in Penicillium chrysogenum

Abstract The specific activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase changed when Penicillium chrysogenum was grown on different carbon sources. In the presence of 2% lactose, the activities of these enzymes were approximately 25–35% lower than those in media containing 2% glucose or 2% fructose. We assume that an increase in cAMP concentration was responsible for the observed decreases in the enzyme activities, because a higher cAMP concentration could be detected when the mycelium was grown in a medium containing solely lactose as carbon source. The likely role played by cAMP in the regulation was also demonstrated by the addition of either cAMP or caffeine to the medium.     

Maternal effect for genes encoding 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase in Drosophila melanogaster

We studied the maternal effect for two enzymes of the pentose cycle, 6-phosphogluconate dehydrogenase (6PGD) and glucose-6-phosphate dehydrogenase (G6PD), using a genetic system based on the interaction of Pgd^? and Zw^? alleles, which inactivate 6PGD and G6PD, respectively. The presence and formation of the enzymes was investigated in those individuals that had not received the corresponding genes from the mother. We revealed maternal forms of the enzymes, detectable up to the pupal stage. The activities of “maternal” 6PGD and G6PD per individual increased 20-fold to 30-fold from the egg stage to the 3rd larval instar even in the absence of normal Pgd and Zw genes. Immunologic studies have shown that the increase in 6PGD activity is due to an accumulation of the maternal form of the enzyme molecules. We revealed a hybrid isozyme resulting from an aggregation of the subunits of isozymes controlled by the genes of the mother and embryo itself. These results indicate that the maternal effect in the case of 6PGD is due to a long-lived stable mRNA transmitted with the egg cytoplasm and translated during the development of Drosophila melanogaster.     

Genetic studies on free-ranging macaques of Cay Santiago. II. 6-phosphogluconate dehydrogenase and NADH-methemoglobin reductase (NADH-diaphorase).

For the population of 395 semi-free-ranging rhesus macaques (Macaca mulatta) that inhabited Cayo Santiago in 1976, 6-phosphogluconate dehydrogenase phenotypes of 378 animals were determined. Three phenotypes, controlled by two autosomal codominant alleles,PGD^A andPGD^B, were found by electrophoretic methods. The frequencies of the alleles are 0.898 and 0.102, respectively. The population, composed of five troops and peripheral males, is in Hardy-Weinberg equilibrium at this locus. The allele frequencies at the 6-phosphogluconate dehydrogenase locus in the population in 1976 were compared with frequencies in 1973; a statistically significant difference was found in one troop. The phenotypes of NADH-methemoglobin reductase (NADH-diaphorase) were determined electrophoretically for 372 animals. These phenotypes are probably the products of two autosomal codominant alleles,Dia¹ andDia², with frequencies of 0.786 and 0.214, respectively. The population is in equilibrium at this locus also. Tests of homogeneity at the dehydrogenase and reductase loci indicate that the allele frequencies are significantly different among the five troops in the population. Observed and expected phenotypic ratios in progeny were compared at the dehydrogenase and the reductase loci. The only significant deviation from expectation occurs among offspring of mothers heterozygous at the reductase locus. The observed distributions of alleles at the 6-phosphogluconate dehydrogenase locus and the NADH-methemoglobin reductase locus are probably the results of stochastic processes.     

Membrane thiol-disulfide status in glucose-6-phosphate dehydrogenase deficient red cells. Relationship to cellular glutathione

The behavior of glucose-6-phosphate dehydrogenase (G6PD)-deficient red cell membrane proteins upon treatment with diamide, the thiol-oxidizing agent (Kosower, N.S. et al. (1969) Biochem. Biophys. Res. Commun. 37, 593–596), was studied with the aid of monobromobimane, a fluorescent labeling agent (Kosower, N.S., Kosower, E.M., Newton, G.L. and Ranney, H.M. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 3382–3386) convenient for following membrane thiol group status. In diamide-treated G6PD-deficient red cells (and in glucose deprived normal cells), glutathione (GSH) is oxidized to glutathione disulfide (GSSG). When cellular GSH is absent, membrane protein thiols are oxidized with the formation of intrachain and interchain disulfides. Differences in sensitivity to oxidation are found among membrane thiols. In diamidetreated normal red cells, GSH is regenerated in the presence of glucose and membrane disulfides reduced. In G6PD-deficient cells, GSSG is not reduced, and the oxidative damage (disulfide formation) in the membrane not repaired. Reduction of membrane disulfides does occur after the addition of GSH to these membranes. A direct link between the thiol status of the cell membrane and cellular GSH is thereby established. GSH serves as a reductant of membrane protein disulfides, in addition to averting membrane thiol oxidation.     

Genetic studies of free-ranging macaques of Cayo Santiago. I. Description of the population and some nonpolymorphic red cell enzymes.

Phenotypes of eight red cell enzymes at nine genetic loci were determined in the semi-free-ranging population of rhesus macaques; Macaca mulatta, that inhabit Cayo Santiago. The following enzymes were examined electrophoretically: adenosine deaminase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, indophenol oxidase, lactate dehydrogenase, malate dehydrogenase, phosphoglucomutase-1, phosphoglumutase-2, and purine nucleoside phosphorylase. Hemolysates from at least 372 animals were analyzed, and no variants of the enzymes were observed with the exception of malate dehydrogenase. Three animals displaying a variant form of malate dehydrogenase were found.     

Schistosoma mansoni and Schistosoma japonicum: comparison of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in adults.

Glucose-6-phosphate dehydrogenase activity in paired adult Schistosoma mansoni is about twice as great as in paired adult Schistosoma japonicum. 2. 6-phosphogluconate dehydrogenase activity accounts for 25.8% of the measured production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in S. japonicum but only 8.6% of the measured production of NADPH in S. mansoni. 3. These data suggest a species difference in 6-phosphogluconate metabolism.     

Purification and properties of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from a methanol-utilizing yeast,Candida boidinii

Glucose-6-phosphate dehydrogenase (d-glucose-6-phosphate: NADP oxidoreductase, EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6-phospho-d-gluconate: NADP oxidoreductase, EC 1.1.1.44) were purified approx. 1700 fold and 330 fold, respectively, from Candida boidinii grown on methanol. The final enzyme preparations were homogeneous as judged by polyacrylamide gel electrophoresis. The molecular weights of the enzymes were estimated to be 118 000 and 110 000, respectively. Both enzymes are composed of two probably identical subunits and the molecular weights of the polypeptide chains were calculated to be 61 000 and 58 000, respectively.From a consideration of enzyme activities and types of inhibition by different metabolites the role of these two enzymes in glucose- and methanol-metabolism is discussed.     

Effects of insulin on the adaptation of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in rat adipose tissue

1.

1. The effects of insulin on adipose tissue glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were studied.     

The influence of temperature on glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase and the regulation of these enzymes in a mesophilic and a thermophilic cyanobacterium

The activities and kinetics of the enzymes G6PDH (glucose-6-phosphate dehydrogenase) and 6PGDH (6-phosphogluconate dehydrogenase) from the mesophilic cyanobacterium Synechococcus 6307 and the thermophilic cyanobacterium Synechococcus 6716 are studied in relation to temperature. In Synechococcus 6307 the apparent K _m's are for G6PDH: 80M (substrate) and 20M (NADP⁺); for 6PGDH: 90M (substrate) and 25M (NADP⁺). In Synechococcus 6716 the apparent K _m's are for G6PDH: 550M (substrate) and 30M (NADP⁺); for 6PGDH: 40M (substrate) and 10M (NADP⁺). None of the K _m's is influenced by the growth temperature and only the K _m's of G6PDH for G6P are influenced by the assay temperature in both organisms. The idea that, in general, thermophilic enzymes possess a lower affinity for their substrates and co-enzymes than mesophilic enzymes is challenged.Although ATP, ribulose-1,5-bisphosphate, NADPH and pH can all influence the activities of G6PDH and 6PGDH to a certain extent (without any difference between the mesophilic and the thermophilic strain), they cannot be responsible for the total deactivation of the enzyme activities observed in the light, thus blocking the pentose phosphate pathway.Abbreviations G6PDH glucose-6-phosphate, dehydrogenase - 6PGDH 6-phosphogluconate dehydrogenase - G6P glucose-6-phosphate - 6PG 6-phosphogluconate - RUDP ribulose-1,5-bisphosphate - Tricine N-Tris (hydroxymethyl)-methylglycine     

Enzyme patterns in D. melanogaster imaginal discs: distribution of glucose-6-phosphate and 6-phosphogluconate dehydrogenase

Distribution of glucose-6-phosphate dehydrogenase (G6PD) and 6-phospho-gluconate dehydrogenase (6PGD) in imaginal discs of Drosophila melanogaster was determined. Differential patterns of staining were found in all discs examined, i.e., eye-antennal, wing, leg, labial and genital. By using null mutants for either G6PD or 6PGD, the enzymes were shown to have the same distribution patterns. Staining with glucose-6-phosphate as a substrate resulted in the detection of both G6PD and 6PGD. Results of staining discs from homoeotic mutants indicate that the enzyme distribution patterns are under genetic control. In the presence of the homoeotic engrailed (en) mutation which transforms posterior wing compartment into anterior, the G6PD pattern of the posterior compartment of the wing disc was specifically transformed toward that of the anterior compartment. The bithorax series of homoeotic mutants was similarly investigated. The bithorax (bx3) mutation transforms the anterior part of the haltere to anterior wing blade. Similarly the G6PD pattern in the anterior haltere disc transforms to that of anterior wing disc. The complimentary transformation, postbithorax (pbx) results in a change of the posterior part of the haltere to posterior wing, which is likewise reflected in an altered staining pattern for G6PD in the posterior portion of the haltere disc. The combination of the bx3 and pbx resulted in a staining pattern of the haltere disc virtually indistinguishable from the normal wing disc.     

Red cell glucose-6-phosphate dehydrogenase deficiency among Andhras

Sixty-eight Andhra males and 45 Andhra females from Visakhapatnam town of Andhra Pradesh, India have been investigated for G-6-PD deficiency. The GdB- gene has a frequency of 4.41% among males. No G-6-PH deficient females were detected. The present data have been compared with the available tribal and non-tribal data from Andhra Pradesh. It is observed that the present sample, though non-tribal in nature, presents a relatively considerable frequency of the GdB- gene.     

Selective precipitation of phosphofructokinase,glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from rat erythrocyte hemolysates by polyethylene glycol

Precipitation profiles of phosphofructokinase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase have been established in the range of 0–16% PEG at different pH (5–7) values. Precipitation generally occurred between narrow limits of polyethylene glycol. The polymer concentration needed to reach any level of enzyme precipitation is dependent on pH. Particular conditions (% PEG and pH) for the selective enzyme enrichment have been determined.