Primate red cell enzymes: glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase

Glucose-6-phosphate dehydrogenase (E. C.: 1.1.1.49) phenotypes and 6-phosphogluconate dehydrogenase (E. C.: 1.1.1.44) phenotypes were determined by starch-gel electrophoresis of red cell hemolysates of Galago crassicaudatus subspp., Propithecus verreauxi, Lemur spp., Hapalemur griseus, and Macaca mulatta. A single glucose-6-phosphate dehydrogenase (G6PD) phenotype was found in each species. A single 6-phosphogluconate dehydrogenase (6PGD) phenotype was found in Lemur spp., Hapalemur griseus, and Galago crassicaudatus argentatus. In a group of six Propithecus verreauxi, three 6PGD phenotypes, PGD A, PGD AB, and PGD B, were found. Three phenotypes, PGD A, PGD AB, and PGD B, were found in 38 G. c. crassicaudatus. The three phenotypes in each species are apparently the products of two codominant autosomal alleles, PGD^A and PGD^B. The frequency of PGD^A in G. c. crassicaudatus is 0.263. A population of 260 free-ranging macaques displays a polymorphism at the 6PGD locus. Three phenotypes, PGD A, PGD AB, and PGD B, were found. These also appear to be controlled by two codominant autosomal alleles, PGD^A and PGD^B the frequency of PGD^A = 0.913. Additional analysis of three well-defined troops within the macaque population indicated that there are no significant differences between the troops or within the population at the 6PGD locus.     

Glucose-6-phosphate dehydrogenase and 6-phosphogluconic acid dehydrogenase of wild oat seeds

The presence of the initial enzymes of the pentose phosphate pathway, namely glucose-6-phosphate dehydrogenase and 6-phosphogluconic acid dehydrogenase, has been demonstrated in dormant seed of wild oat. Before a partial characterization of these enzymes was made, an inherent NADP-reducing activity and an enzyme deactivating component, both present in the crude extract, were removed by ammonium sulphate precipitation and subsequent desalting. Both enzymes were then shown to be NADP-specific. Typical Michaelis-Menten kinetics were shown by each enzyme towards NADP and their respective substrates. Soluble cytoplasmic dehydrogenase enzymes were present in both embryo and endosperm extracts.     

Glucose-6-phosphate dehydrogenase Boston

Summary A hitherto undescribed variant of erythrocyte glucose-6-phosphate dehydrogenase (G-6-PD) activity, G-6-PD Boston, is described in a 24-year-old Caucasian male of Polish-Jewish ancestry. A marked decrease in red cell G-6-PD activity was associated, in this individual, with a compensated hemolytic process. The electrophoretic mobility of the partially purified enzyme on cellulose acetate at pH 9.1 and on starch gel was indistinguishable from normal but the apparent K_m for both G-6-PD (18–21 M) and NADP (1.7–2.2) was significantly decreased. Preliminary evidence supports the concept that G-6-PD Boston may not be extremely rare among this particular population group.     

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.     

Characterization of glucose-6-phosphate dehydrogenase and 6-phosphogluconic acid dehydrogenase from hazel cotyledons

NADP reduction was shown to occur in a crude cytosolic extract from the cotyledonary material of hazel seed prior to the addition of erogenous dehydrogenase substrate. This activity interfered with the assay of glucose-6-phosphate dehydrogenase and 6-phosphogluconic acid dehydrogenase activities. The inherent NADP reduction was removed by ammonium sulphate fractionation. Subsequent de-salting of the resulting partially-purified fraction permitted assay of G6PDH and 6PGDH. Both enzymes were shown to be NADP specific. Typical Michaelis-Menten kinetics were shown for each enzyme, towards NADP and their respective substrate.     

Selection of Escherichia coli mutants lacking glucose-6-phosphate dehydrogenase or gluconate-6-phosphate dehydrogenase

Glucose is metabolized in Escherichia coli chiefly via the phosphoglucose isomerase reaction; mutants lacking that enzyme grow slowly on glucose by using the hexose monophosphate shunt. When such a strain is further mutated so as to yield strains unable to grow at all on glucose or on glucose-6-phosphate, the secondary strains are found to lack also activity of glucose-6-phosphate dehydrogenase. The double mutants can be transduced back to glucose positivity; one class of transductants has normal phosphoglucose isomerase activity but no glucose-6-phosphate dehydrogenase. An analogous scheme has been used to select mutants lacking gluconate-6-phosphate dehydrogenase. Here the primary mutant lacks gluconate-6-phosphate dehydrase (an enzyme of the Enter-Doudoroff pathway) and grows slowly on gluconate; gluconate-negative mutants are selected from it. These mutants, lacking the nicotinamide dinucleotide phosphate-linked glucose-6-phosphate dehydrogenase or gluconate-6-phosphate dehydrogenase, grow on glucose at rates similar to the wild type. Thus, these enzymes are not essential for glucose metabolism in E. coli.     

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.     

The foetal development of lactate dehydrogenase isoenzymes, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from human striated muscle

1. Human foetal skeletal muscles involved in support and in periodic contractility were studied for their content of total extractable lactate dehydrogenase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities as well as for the relative distribution of lactate dehydrogenase isoenzymes. 2. During foetal development a linear steady increase in total lactate dehydrogenase activity as well as a linear decrease in the H/M sub-unit ratio of the isoenzymes was found. 3. No significant changes were found in the activities of the enzymes of the hexose monophosphate shunt (C-6 oxidation). 4. The changes found suggest a steady increased synthesis of lactate dehydrogenase M-sub-units in human skeletal muscles during foetal development. 5. The weekly changes in the total lactate dehydrogenase activity and in lactate dehydrogenase isoenzymes are lower in muscles involved in support than in those involved in periodic contractility. 6. These findings, together with the literature available, are consistent with the morphological fact that foetal development of skeletal muscles mostly concerns the white muscle fibres and not the red muscle fibres.     

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.     

X-linked glucose-6-phosphate dehydrogenase (G6PD) and autosomal 6-phosphogluconate dehydrogenase (6PGD) polymorphisms in baboons

Electrophoretic polymorphisms of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) were examined in captive colonies of five subspecies of baboons (Papio hamadryas). Phenotype frequencies and family data verified the X-linked inheritance of the G6PD polymorphism. Insufficient family data were available to confirm autosomal inheritance of the 6PGD polymorphism, but the electrophoretic patterns of variant types (putative heterozygotes) suggested the codominant expression of alleles at an autosomal locus. Implications of the G6PD polymorphism are discussed with regard to its utility as a marker system for research on X-chromosome inactivation during baboon development and for studies of clonal cell proliferation and/or cell selection during the development of atherosclerotic lesions in the baboon model.     

Glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from Lactobacillus casei: responses with different modulators

Glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) were separated and partially purified from glucose-grown cells of Lactobacillus casei. The enzymes had similar pH optima, thermosensitivity and molecular weights. They had different net charges and their pI values were 5.38 and 4.52, respectively. Histidine, arginine, lysine and cysteine residues were essential for the activity of G6PD, and all the above amino acids with the exception of lysine were required for 6PGD activity. Mg2+ activated 6PGD up to 15 mM concentration, above which it was inhibitory. It had no effect on G6PD activity. G6PD was specific for NADP+, but 6PGD showed some activity with NAD+ as the cofactor, although it was essentially NADP(+)-preferring. Both the enzymes, were inhibited by NADPH. 6PGD was also inhibited by its product, ribulose 5-phosphate. ATP inhibited 6PGD only at subsaturating concentrations of NADP+. The inhibition was sigmoidal in the absence of Mg2+ and hyperbolic in its presence.     

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.     

Glucose-6-phosphate dehydrogenase in Thailand

Summary Erythrocyte G6PD from 1157 nondeficient Thai males was studied electrophoretically. The enzyme from four subjects showed abnormal mobility. Characterization of the enzyme revealed three new variants: G6PDs Ayutthaya (n=2), S-Sakorn, and Chao Phya.     

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.