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PubMed1982

[Purification and some properties of molecular forms of 6-phosphogluconate dehydrogenase from rat liver].

Using stepwise protein fractionation by (NH4)2SO4 and ion-exchange chromatography on CM-cellulose, DEAE-cellulose and SP-Sephadex, two isoforms of 6-phosphogluconate dehydrogenase, A and B, from rat liver were obtained. The method developed allows to achieve complete separation of these forms and to obtain preparative amounts of the protein with specific activities of 5.7 and 10.7, respectively. The native enzyme forms A and B have molecular weights of 107000 and are represented by dimers composed of subunits with identical molecular weights equal to 54000. Both isoforms have a pH optimum at 8.5 and reveal different sensitivity to MgCl2 and MnCl2. The tetrahedron-shaped ions (phosphate, molibdate, arsenate) inhibit the both molecular forms of the enzyme, The Arrhenius plots for the reaction rate are uninterrupted lines within the temperature range of 21-44 degrees; the values of activation energy and the temperature coefficient for isoforms A and B are 12750 and 13500 cal/mole and 2.05 and 2.15, respectively.

Animals↗

PubMed1990

Variations in manganese effect on 6-phosphogluconate dehydrogenases from the thyroid and liver of the mouse and an evidence for non-interchangeability of manganese and magnesium.

Both manganese (Mn) and magnesium (Mg) are known to activate 6-phosphogluconate dehydrogenase (6-PGDH). Yet in the present study none of the metal ions stimulated 6-PGDH from the thyroid of mice, but Mn alone stimulated the enzyme from the liver. Such a stimulatory effect of Mn on the liver enzyme was seen regardless of the presence of Mg, This suggests that the reaction sites for the two ions must be apart from one another or that the affinity of Mn is stronger than that of Mg. The enzyme preparations from livers of those mice which had been administered intraperitoneally with excess of Mn for 1 - 14 days were greatly stimulated by further in vitro addition of Mn, whereas the enzyme sources from the thyroids thus treated were almost insensitive to Mn in vitro. The results indicate that cellular Mn hardly reaches the levels for maximal stimulation of the enzyme in the liver. In addition, some sex difference was observed in the Mn effect on 6-PGDH from the liver.

Animals↗

PubMed1995

Structure of 6-phosphogluconate dehydrogenase refined at 2 A resolution.

The X-ray unliganded structure of 6-phosphogluconate dehydrogenase (E.C. 1.1.1.44) (6-PGDH) from sheep liver has been determined at 2A resolution and refined to a final R-factor of 19.8% for 35 031 unique reflections. The enzyme is dimeric, each subunit being comprised of an N-terminal coenzyme-binding domain with a Rossmann fold, a large all-helical domain and a small C-terminal tail. The model contains 473 residues, three sulfate ions and 346 water molecules; the two best defined sulfates are found in the active site. This structure, based on improved diffraction data, is an extension of the 2.5 A, resolution model reported earlier. It has good geometry with 92% of the residues falling in the most favoured areas of the Ramachandran plot. Several unusual features are discussed: the incorporation of an alanine in place of the second conserved glycine of the dinucleotide-binding fingerprint; a duplicated five-helix motif which is unique to this enzyme; an extended water network at the dimer interface and a C-terminal tail which is incorporated within the second subunit, forming not only a major part of the dimer interface but also part of the active site.

Journal Article↗

PubMed1993

Chemical mechanism of 6-phosphogluconate dehydrogenase from Candida utilis from pH studies.

The pH dependence of kinetic parameters and dissociation constants for competitive inhibitors was determined in order to obtain information on the chemical mechanism for the 6-phosphogluconate dehydrogenase reaction from Candida utilis. A mechanism is proposed in which an active site general base accepts the proton from the 3-hydroxyl concomitant with hydride transfer at C-3; the resulting 3-keto intermediate is decarboxylated to give the enol of ribulose 5-phosphate, followed by tautomerization of the enol to the keto product with the assist of a second enzyme residue acting as a general acid. There is also a requirement for an ionized phosphate of 6-phosphogluconate and ribulose 5-phosphate for optimum binding. The maximum velocity is pH dependent, decreasing at high and low pH giving pK values of 6 and 10, while the V/K for 6-phosphogluconate decreases at low pH with a slope of 2 yielding pK values of 6.4 and 7.6, respectively, and at high pH with a slope of -1 yielding a pK of 8.2. The 6-sulfogluconate pKi profile decreases at low and high pH giving pK values of 7.1 and 8.5, respectively. The 5-phosphoarabonate and 5-phosphoarabonate pKi profiles show similar behavior giving pK values of 6.5 and 8.8, respectively, for the former and 6.8 and 8.8, respectively, for the latter. The V/K for NADP also decreases at low and high pH giving pKs of 7.5 and 8.1, while the ATP-Ribose pKi profile decreases at low and high pH giving pKs of 7.2 and 8.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Candida↗

PubMed1979

Inhibition of 6-phosphogluconate dehydrogenase (decarboxylating) by glucose 1,6-bisphosphate.

Glucose 1,6-bisphosphate, the powerful common regulator of several key enzymes in carbohydrate metabolism, was found to exert a potent inhibitory effect on the activity of 6-phosphogluconate dehydrogenase (decarboxylating) from yeast and several rat tissues. These findings suggest that glucose 1,6-bisphosphate may have a regulatory influence on the pentose phosphate pathway.

Animals↗

PubMed1997

The gnd gene encoding a novel 6-phosphogluconate dehydrogenase and its adjacent region of Actinobacillus actinomycetemcomitans chromosomal DNA.

A 10-kb DNA fragment containing the gnd gene from Actinobacillus actinomy-cetemcomitans Y4 was isolated and sequenced. The structural gnd gene codes for 6-phosphogluconate dehydrogenase that consists of 484 amino acids. In contrast to the gnd gene in Escherichia coli, Salmonella typhimurium, or Klebsiella pneumoniae, the gnd gene of A. actinomycetemcomitans was not located in the rfb or cps operon. The zwf gene encoding glucose 6-phosphate dehydrogenase, which is another enzyme consisting of pentose-phosphate pathway, sided at 3.8-kb upstream from the gnd gene. A phylogenetic tree based on sequence analyses showed higher homology of 6-phospho-gluconate dehydrogenase of A. actinomycetemcomitans with the eucaryotic enzymes rather than with bacterial enzymes.

Actinobacillus↗

PubMed1989

Cloning and dosage compensation of the 6-phosphogluconate dehydrogenase gene (Pgd+) of Drosophila melanogaster.

Using a heterologous rat cDNA probe, we have identified a 14.7 kbp Drosophila melanogaster genomic clone containing the X-linked gene Pgd+, which encodes the enzyme 6-phosphogluconate dehydrogenase (6PGD). We used in situ hybridization to larval polytene chromosomes, a somatic transient expression assay for enzyme activity, and the rescue of the lethal Pgd- phenotype by germline transformation to verify the identity of the gene. A 7.4 kbp fragment including the gene and approximately 1.2 kbp of upstream and 1.8 kbp of downstream sequences was relocated to autosomal ectopic sites by germline transformation; this transduced gene exhibits levels of enhanced activity in males comparable to those of the indigenous gene at its normal X chromosome locus. We conclude that the sequences responsible for dosage compensation of Pgd+ are included in this fragment.

Animals↗

PubMed2006

Cloning and structural characterization of the 6-phosphogluconate dehydrogenase locus of the medfly Ceratitis capitata and the olive fruit fly Bactrocera oleae.

The pentose phosphate cycle is considered as a major source of NADPH and pentose needed for nucleic acid biosynthesis. 6-Phosphogluconate dehydrogenase (6PGD), an enzyme participating in this cycle, catalyzes the oxidative decarboxylation of 6PGD to ribulose 5-phosphate with the subsequent release of CO(2) and the reduction of NADP. We have determined the genomic sequences of 6PGD of two species of Tephritidae, the medfly Ceratitis capitata and olive fruit fly Bactrocera oleae, and constructed a three-dimensional model of 6PGD of C. capitata based on the homologous known sheep structure. In a comparative study of 6PGD sequences from seven species, all the conserved and variable sites of the enzyme were analyzed and the regions of functional importance were localized, an attempt promoted also by the direct involvement of the enzyme in various human diseases. The enzymes between the two species of Tephritidae have a very high homology and further examination of the variable positions with respect to the highly conserved binding site residues enabled their grouping in three distinct categories, with possible association to dimer formation, functional specificity, and antigenicity. Moreover, placement of sequence differences on the 3-D model suggests probable sites accommodating variations appearing at the allozymic variants of both species.

Amino Acid Sequence↗

PubMed1978

Quantitation of messenger RNA levels for rat liver 6-phosphogluconate dehydrogenase.

Liver poly(A)-containing RNA isolated from rats in different dietary states was translated in a cell free protein synthesizing system employing reticulocyte lysates. Immunoprecipitation of the cell-free reaction products with goat anti-6-phosphogluconate dehydrogenase followed by sodium dodecyl sulfate-urea-gel electrophoresis showed that the induction of this lipogenic enzyme was accompanied by a corresponding increase in the concentration of its specific translatable mRNA.

Animals↗

PubMed1998

Oxidative decarboxylation of 6-phosphogluconate by 6-phosphogluconate dehydrogenase proceeds by a stepwise mechanism with NADP and APADP as oxidants.

Primary kinetic deuterium, 13C, and multiple deuterium/13C-isotope effects on V/K6PG have been measured for the Candida utilis (cu) and sheep liver (sl) 6-phosphogluconate dehydrogenases (6PGDH). With NADP as the dinucleotide substrate, the following values of D(V/K6PG), 13(V/K6PG)H, and 13(V/K6PG)D were measured at pH 8 for cu6PGDH (sl6PGDH): 1.57 +/- 0.08 (1.87 +/- 0.10), 1.0209 +/- 0.0005 (1.0059 +/- 0.000 10), 1.0158 +/- 0.0001 (1.0036 +/- 0.0008). With APADP as the dinucleotide substrate, values for the above isotope effects at pH 8 are as follows: 2.98 +/- 0.08 (2.47 +/- 0.06), 1. 0106 +/- 0.0002 (1.0086 +/- 0.000 09), and 0.9934 +/- 0.0003 (0.9950 +/- 0.0003). Results indicate the oxidative decarboxylation of 6PG to the 1,2-enediol of ribulose 5-phosphate proceeds via a stepwise mechanism with hydride transfer preceding decarboxylation in all cases. The inverse 13C-isotope effect observed with APADP and 6PG-3d may reflect a preequlibrium isotope effect on the binding of 6PG preceding hydride transfer. Deuterium-isotope effects on V, V/KNADP, and V/K6PG are identical at all pHs and for both enzymes. The primary deuterium-isotope effect on V/K6PG for both enzymes is constant at pH values below the pK in the pH profile for V/K6PG, and decreases as the pH increases. Data suggest the development of rate limitation by a step or steps other than the hydride-transfer step as the pH is increased.

Animals↗

PubMed1979

[Genetic polymorphism of erythrocytic enzymes in the Rennes area. Frequency of adenylate kinase, esterase D, adenosine deaminase, 6-phosphogluconate dehydrogenase, glutamate-pyruvate transaminase and glyoxyalase I phenotypes].

Blood donors from the Centre Régional de Transfusion Sanguine de Rennes were investigated for the phenotypic distribution of seven enzymatic systems : adenylate kinase, adenosine deaminase, esterase D, 6-phosphogluconate dehydrogenase, glutamate-pyruvate transaminase, phosphoglucomutase, and glyoxalase I. Two unusual phenotypes were observed: phenotype 6-1 for adenosine deaminase and phenotype 3-1 for transaminase GPT. For five of these enzymes, the statistical analysis points out significant differences in one or several of the European populations described in the literature.

Adenosine Deaminase↗

PubMed2003

Molecular cloning and characterization of rice 6-phosphogluconate dehydrogenase gene that is up-regulated by salt stress.

The pentose phosphate pathway (PPP) is the important metabolism pathway in plant. In the present study, a cDNA encoding one of the key enzymes of PPP, 6-phosphogluconate dehydrogenase(6PGDH), was isolated from rice and designated as Os6PGDH. The Os6PGDH encoding protein is a cytosolic isoenzyme according to the absence of plastid transit peptide at the N-terminus. The full-length cDNA of 1751 bp encodes 480 amino acids and its putative protein sequence is 94%, 84% and 83% identical to maize, spinach and alfalfa 6PGDHs respectively. Comparison of the cloned mRNA sequence with that of the genomic sequence from the Rice Genome Project showed a simple genomic organization devoid of introns in the translated region of the gene. RT-PCR experiments revealed that Os6PGDH expression was high in inflorescence, low in root and embryos but almost absent in leaves. Furthermore, Os6PGDH was up-regulated in the shoots under salt stress. It is suggested that 6PGDH in plant may play an important role in cell division and salt response.

Amino Acid Sequence↗

PubMed1989

Growth-rate-dependent regulation of 6-phosphogluconate dehydrogenase level mediated by an anti-Shine-Dalgarno sequence located within the Escherichia coli gnd structural gene.

Previous work has shown that in Escherichia coli K-12 growth-rate-dependent regulation of expression of 6-phosphogluconate dehydrogenase, encoded by the gnd gene, occurs at the posttranscriptional level and is mediated by a negative control element that lies deep in the coding sequence, somewhere between codons 48 and 118. Deletion analysis of a growth-rate-regulated gnd-lacZ translational fusion showed that the element is the segment of gnd mRNA between codons 67 and 78 that is complementary to an extensive portion of the gnd ribosome-binding site, including its Shine-Dalgarno sequence. The boundaries of the element were further defined by the cloning of a synthetic "internal complementary sequence." The core internal complementary sequence element effected growth-rate-dependent regulation when placed at several sites between codon 40 and codon 69, but it severely reduced gene expression when moved to codon 13. The effect on regulation of single and double mutations introduced into the element by site-directed mutagenesis correlated with the ability of the respective mRNAs to fold into secondary structures that sequester the ribosome-binding site. Thus the gnd gene's internal regulatory element appears to function as a cis-acting antisense RNA.

Base Sequence↗

PubMed1977

Regulation of enzyme turnover during tissue differentiation. Studies on 6-phosphogluconate dehydrogenase in rabbit mammary gland in organ culture.

(1) Explants of mammary gland from mid-pregnant rabbits were cultured in Medium 199 in the presence or absence of insulin, prolactin and cortisol. (2) Antiserum to 6-phosphogluconate dehydrogenase was raised in sheep and used to titrate the amount of enzyme activity present in explant extracts. Changes in enzyme activity were found to be due to corresponding changes in amount of the enzyme. The greatest increases in the amount of the enzyme were only brought about by culture of explants in the presence of hormones (insulin, prolactin and cortisol) in Medium 199 which contained glucose. (3) The increases in the amount of the enzyme were similar in explants cultured with hormones in Medium 199 which contained 1.39 mM, 5.55 mM or 55.5 mM glucose. (4) When explants were cultured with hormones in Medium 199 which contained glucose (5.55 mM) for 24 h and then cultured with hormones in Medium 199 which contained glycerol (10.9 mM), a decrease in the amount of the enzyme occurred. In contrast, the culture of explants with hormones in Medium 199 which contained glycerol (10.9 mM) for 24 h followed by transfer of the explants to medium which contained glucose (5.55 mM) resulted in an increase in the amount of the enzyme to reach values which were not different from those found in explants cultured throughout with hormones in Medium 199 which contained glucose.

Animals↗

PubMed1984

Relationships between the H and A-O blood types, phosphohexose isomerase and 6-phosphogluconate dehydrogenase red cell enzyme systems and halothane sensitivity, and economic traits in a superior and an inferior selection line of swiss landrace pigs.

Associations between production traits and the genes for halothane sensitivity (HAL), S, A and H blood group systems and phosphohexose isomerase (PHI) and 6-phosphogluconate dehydrogenase (6-PGD) enzyme systems were investigated in two lines of pigs selected for an index. The phenotypic variance-covariance matrix of the index included backfat thickness and daily gain, whereas the genetic variance-covariance matrix included daily gain, feed conversion and percentage of lean meat. The experiment was conducted at the experimental station of the Institute of Animal Production and has been underway since 1973. The same index was applied but in two opposite directions to give a superior and inferior line in relation to the production traits. One hundred twenty-nine animals of the superior line in the seventh generation and 88 animals of the inferior line in the sixth generation were studied. Forty-two percent (54/129) of the animals of the superior line were halothane-positive. No animals in the inferior line were halothane reactors. Of the halothane-positive pigs, 70.4% (38/54) in the superior line had the HaHa and 94.4% (51/54) had the SsSs genotype, whereas only 4% (3/75) of the HaHa and 12% (9/75) of the SsSs pigs were halothane-negative. By practicing selection at the H and S loci, it seems possible to efficiently reduce halothane sensitivity in Swiss Landrace pigs. In pigs of the superior line, there were significant differences in percentage of lean meat, carcass length, pH1 (pH value at 45 min to 1 h postmortem, M. longissimus) and reflectance values among genotypes of the HAL, S and H systems and among some genotypes of the 6-PGD system. Poorest meat quality, highest percentage of lean meat and shortest carcass length were observed in pigs homozygous for the alleles HALn, Ss, Ha, PHIB and 6-PGDA. In the inferior line, these associations were absent. As the HAL locus is associated with the above mentioned production traits, linkage disequilibria may explain the observed associations among the H, S, PHI and 6-PGD types and production traits.

Alleles↗

PubMed1991

Differential solubility behaviour in poly(ethylene glycol) solutions of glucose 6-phosphate and 6-phosphogluconate dehydrogenases from bone marrow, reticulocytes and erythrocytes.

Precipitation of glucose 6-phosphate dehydrogenase by poly(ethylene glycol) depends on both pH and the source of haemolysate. An increase in pH from 5 to 7 leads to an increase in the polymer concentration required for precipitation. At any pH, polymer concentration needed to precipitate the enzyme increases in the order bone marrow less than reticulocytes less than erythrocytes. This differential behaviour seems to be due to variations on the effect of pH on the state of aggregation and/or differences in the intrinsic solubility of the enzyme present in the three haemolysates. In contrast, precipitation profile of 6-phosphogluconate dehydrogenase only slightly moves towards higher concentrations of PEG when raising the pH from 5 to 7, being similar at each single pH in the three haemolysates.

Animals↗

PubMed1998

6-Phosphogluconate dehydrogenase is a 45-kDa antigen recognized by S4D5, a monoclonal antibody specific to vanadocytes in the vanadium-rich ascidian Ascidia sydneiensis samea.

We previously prepared a monoclonal antibody, S4D5, specific to vanadocytes, vanadium-containing blood cells, in the vanadium-rich ascidian Ascidia sydneiensis samea. Here, we demonstrate that a 45-kDa antigen recognized by S4D5 is 6-phosphogluconate dehydrogenase (6-PGDH), an enzyme of the pentose phosphate pathway, based on cDNA isolation of RNA samples from blood cells of the ascidian. Western blot analysis confirmed an abundance of 6-PGDH protein in the vanadocytes and localization of 6-PGDH in the soluble extract of the blood cells. Soluble protein exhibited a correspondingly high level of 6-PGDH enzymatic activity. Ascidians are known to selectively accumulate high levels of vanadium in vanadocytes, and the highest recorded concentration of accumulated vanadium is 350 mM, which is 10(7) times the concentration in sea water. Almost all vanadium ions are reduced to the +3 oxidation state via the +4 oxidation state in vanadocytes, indicating that reducing agents must participate in the accumulation. On the other hand, vanadium ions in the +5 oxidation state are reduced to the +4 oxidation state by the presence of NADPH in vitro. Together, these observations suggest that NADPH produced in the pentose phosphate pathway may conjugate the reduction of vanadium from the +5 oxidation state through the +4 oxidation state in vanadocytes of ascidians.

Amino Acid Sequence↗

PubMed1994

Evolutionary inferences from DNA variation at the 6-phosphogluconate dehydrogenase locus in natural populations of drosophila: selection and geographic differentiation.

Several allozyme-coding genes in Drosophila melanogaster show patterns suggesting that polymorphisms at these loci are targets of balancing selection. An important question is whether these genes have similar distributions of underlying DNA sequence variation which would indicate similar evolutionary processes occurring in this class of loci. One such locus, 6-phosphogluconate dehydrogenase (Pgd), has previously been shown to exhibit clinal variation for Fast/Slow electromorph variation in the United States and Australia, unusually large electromorph frequency differences between the United States and Africa, and other patterns indicative of selection. We measured four-cutter DNA restriction site and allozyme variation at Pgd among 142 D. melanogaster X chromosomes collected from several geographic regions including North Carolina, California, and Zimbabwe (Africa). We also sequenced a representative sample of 13 D. melanogaster Pgd genes collected in North Carolina and a single copy of Pgd from the sibling species, Drosophila simulans. While some population genetic models predict excess DNA polymorphism in genes which are targets of balancing selection, the D. melanogaster samples from the United States had significantly reduced levels of DNA polymorphism and extraordinarily high levels of linkage disequilibrium, providing evidence of hitchhiking effects of advantageous mutants at Pgd or at linked sites. Therefore, while selection has probably influenced the distribution of DNA variation at Pgd, the precise nature of these selective events remains obscure. Since the Pgd region appears to have low rates of crossing over, the reduced level of variation at this locus supports the idea that recombination rates are important determinants of levels of DNA polymorphism in natural populations. Furthermore, while patterns of allozyme variation are very similar at Pgd and Adh, the DNA data show that the evolutionary histories of these genes are dramatically different. We observed extensive differences in the amount and distribution of variation in D. melanogaster Pgd samples from the United States and Zimbabwe which cannot be explained by differential selection on the Fast/Slow polymorphism in these two geographic regions. Thus, genetic drift among partially isolated populations has also been an important factor in determining the distribution of variation at Pgd in D. melanogaster. Finally, we assayed four-cutter variation at Pgd in a sample of 19 D. simulans X chromosomes and observed reduced levels of DNA variability and high levels of linkage disequilibrium. These patterns are consistent with predictions of some hitchhiking models.

Animals↗