Gene/Protein Disease Symptom Drug Enzyme Compound
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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)

1. In the lung and liver of tocopherol-deficient rats, the activities of glutathione peroxidase and glucose 6-phosphate dehydrogenase were increased substantially, suggesting an important role for both enzymes in protecting the organ against the deleterious effects of lipid peroxides. 2. Facilitation of the glutathione peroxidase reaction by infusing t-butyl hydroperoxide caused the oxidation of nicotinamide nucleotides and glutathione, resulting in a concomitant increase in the rate of release of oxidized glutathione into the perfusate. Thus the rate of production of lipid peroxide and H2O2 in the perfused organ could be compared by simultaneous measurement of the rate of glutathione release and the turnover number of the catalase reaction. 3. On hyperbaric oxygenation at 4 X 10(5)Pa, H2O2 production, estimated from the turnover of the catalase reaction, was increased slightly in the liver, and glutathione release was increased slightly, in both lung and liver. 4. Tocopherol deficiency caused a marked increase in lipid-peroxide formation as indicated by a corresponding increase in glutathione release under hyperbaric oxygenation, with a further enhancement when the tocopherol-deficient rats were also starved. 5. The study demonstrates that the primary response to hyperbaric oxygenation is an elevation of the rate of lipid peroxidation rather than of the rate of formation of H2O2 or superoxide.
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PMID:Oxygen toxicity in the perfused rat liver and lung under hyperbaric conditions. 1 54

The BIOSTATOR Systems have an on-line glucose analyzer for use with whole blood. This analyzer utilizes a novel enzyme (glucose oxidase) membrane configuration and an electrochemical cell to measure the H2O2 generated. The analyzer response is fast, accurate, precise, stable, and linearly related to the blood glucose concentration over the full range of clinical interest. Extensive correlation studies have been completed to show the agreement between this analyzer and the U.S. Food and Drug Administration's recommended hexokinase-glucose-6-phosphate dehydrogenase procedure. In addition, studies on potentially interfering substance and the differences in whole blood and plasma glucose levels have been completed.
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PMID:Evaluation of the BIOSTATOR systems glucose analyzer. 29 37

The nematicidal compound alpha-terthienyl from roots of Tagetes species generates upon irradiation with near ultraviolet light reactive oxygen species on which the in vitro nematicidal activity depends. This system was studied by following the inhibition of glucose-6-phosphate dehydrogenase by photoactivated alpha-terthienyl and protection of the enzyme activity in the absence of oxygen and by various additions. Addition of mannitol, benzoate, superoxide dismutase or catalase did not have any effect nor did H2O2. This suggests that OH., O-.2, and H2O2 are not the reactive oxygen species involved. The enzyme was protected against photoactivated alpha-terthienyl in air-saturated solutions by singlet oxygen quenchers such as histidine, methionine, tryptophan, bovine serum albumin, and NaN3. Furthermore, inactivation of the enzyme was about 3.5 times faster in D2O than in H2O. When alpha-terthienyl in CH2Cl2 was irradiated in the presence of the olefin adamantylideneadamantane, a stable dioxetane was formed which decomposed to adamantanone when heated above its melting point. These results indicate a singlet oxygen-mediated process.
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PMID:Photoactivation of the nematicidal compound alpha-terthienyl from roots of marigolds (Tagetes species). A possible singlet oxygen role. 42 57

(1) Oxygen uptake and lactate production of different strains of ascites tumor cells were assayed after exposure to an extracellular photochemical system known to produce reactive oxygen derivatives. The various cells tested showed differential sensitivity to the treatment, ranging from nearly full inactivation of Ehrlich cells to nearly full resistance of Yoshida cells. (2) Glucose plus succinate added after the treatment reestablished basal oxygen uptake capacity suggesting that the cell membrane was the primary site of damage. This was confirmed by dye-permeabilization and protein leakage in sensitive cells. (3) H2O2 was shown to be the only relevant oxygen derivative in the production of cell damage: catalase was the only externally added agent that protected sensitive cells, and H2O2 (congruent to 10(-3) M) had the same effects as the photochemical treatment. (4) While the absence of catalase is a feature common to all tumors tested, sensitivity to H2O2 appears to be related to cellular levels of glutathione peroxidase and of its subsidiary enzymes glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione synthetase.
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PMID:Differential sensitivity of tumor cells to externally generated hydrogen peroxide. Role of glutathione and related enzymes. 55 3

Filarial parasites, Litomosoides carinii and Setaria cervi, showed great susceptibility to the oxidants generated in vitro by the xanthine/xanthine-oxidase system. In order to counteract such injurious effects, both the filariids possessed an active antioxidant enzymes system. Superoxide dismutase, catalase and glutathione peroxidase were detected in appreciable amounts but glutathione reductase and glucose-6-phosphate dehydrogenase in very low quantities. The former three enzymes were also found to be released by the parasites into the ambient medium. The released enzymes may be responsible for scavenging the host-generated oxidants present in the immediate surroundings of the parasites and thereby enabling them to live comfortably in the host. This Institute-based antifilarial agent namely Compound 82/437 which is 2,2'-dicarbomethoxylamino-5,5'-dibenzimidazolylketone, markedly inhibited catalase and glutathione peroxidase of both L. carinii and S. cervi. The compound, therefore, appears to render the filariids prone to H2O2 toxicity leading to penultimate damage.
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PMID:Antioxidant system of Litomosoides carinii and Setaria cervi: effect of a macrofilaricidal agent. 149 6

The PAR1/SNQ3 gene of S. cerevisiae, which increases resistance to iron chelators in multi-copy transformants, is identical to the YAP1 gene, a yeast activator protein isolated as a functional homologue of the human c-jun oncogene by binding specifically to the AP-1 consensus box. The observed H2O2-sensitivity of par1 mutants has been attributed to an increased sensitivity to reduced oxygen intermediates. Accordingly, par1 mutants did not survive an elevated oxygen pressure and were very sensitive to menadione and methylviologene, two chemicals enhancing the deleterious effects of oxygen. The specific activities of enzymes involved in oxygen detoxification, such as superoxide dismutase, glucose 6-phosphate dehydrogenase and glutathione reductase, were decreased in par1 mutants and increased after PAR1 over-expression. As in the case of oxygen detoxification enzymes, the cellular levels of glutathione were similarly affected. These observations indicate that PAR1/YAP1/SNQ3 is involved in the gene regulation of certain oxygen detoxification enzymes. The finding that H2O2 promotes DNA-binding of human c-jun is consistent with a similar function for PAR1/YAP1/SNQ3 and c-jun in cellular metabolism.
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PMID:The PAR1 (YAP1/SNQ3) gene of Saccharomyces cerevisiae, a c-jun homologue, is involved in oxygen metabolism. 152 53

Primaquine is an important antimalarial drug which causes hemolytic anemia in patients with glucose-6-phosphate dehydrogenase (G6PDH) deficiency, probably due to oxidant generation by its metabolites. One of primaquine's metabolites, 5,6-dihydroxy-8-aminoquinoline (AQD), was found to cause chemiluminescence (CL) in vitro when incubated in the presence of luminol. This CL is inhibited by catalase and deferoxamine, unaffected by mannitol, and stimulated by superoxide dismutase (SOD), suggesting that it is mediated by H2O2. Three antioxidants (daphnetin, ferulate, and maltol), derived from Chinese herbal remedies, inhibited AQD- and H2O2-mediated CL, whereas a fourth, anisodamine, had no effect. Daphnetin also potently inhibited H2O2-mediated lipid peroxidation as measured by the production of thibarbituric acid reacting substances (TBARS). Thus, the possibility is raised that an antioxidant might be able to mitigate the oxidant hemolytic effects of primaquine.
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PMID:Activated oxygen generation by a primaquine metabolite: inhibition by antioxidants derived from Chinese herbal remedies. 156 47

The role of different antioxidant pathways in cultured rat pleural mesothelial cells was studied by exposing the cells to various hydrogen peroxide (H2O2) concentrations and by measuring H2O2 cell cytotoxicity and the capacity of the cells to scavenge H2O2. The antioxidant enzymes, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, and catalase were analyzed biochemically. Catalase and CuZn superoxide dismutase were localized by immunocytochemistry. To enable investigation of the glutathione redox cycle and catalase pathways, glutathione reductase was inactivated with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and catalase was inactivated with aminotriazole. When the cells were exposed to a low, sublethal (0.030 mM) H2O2 concentration, glutathione reductase but not catalase inactivation resulted in a decreased capacity to remove H2O2 from the extracellular medium. When the cells were exposed to a high (0.25 mM) H2O2 concentration, H2O2-scavenging capacity decreased remarkably when catalase was inactivated. When the cells were exposed to 0.1 to 0.5 mM H2O2, cell cytotoxicity (lactate dehydrogenase release) increased significantly if glutathione reductase was inactivated; catalase inactivation resulted in a significant cytotoxicity only at high (greater than or equal to 0.25 mM) H2O2 concentrations. Immunocytochemical studies showed that the cells, both in situ and in vitro, contained low amounts of catalase. This suggests that the results of the catalase-inhibition studies are probably not due to a change in the characteristics of the cells in culture. 3-Aminobenzamide is a compound that is known to prevent NAD depletion through inhibition of poly(ADP-ribose) polymerase during oxidant stress. When intact cells were treated with different antioxidants and exposed to 0.5 mM H2O2, both catalase and 3-aminobenzamide protected the cells completely.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Antioxidant defense mechanisms in cultured pleural mesothelial cells. 162 38

As a variety of eukaryotic cells age, the specific activity of glucose-6-phosphate dehydrogenase (Glu-6-PDH) declines as much as 50%. Because of the central role of this enzyme in metabolism, it is important to define factors responsible for this loss in enzyme activity. We report that Glu-6-PDH from Leuconostoc mesenteroides is rapidly inactivated by micromolar concentrations of Fe2+ and H2O2. Inactivation correlated with the formation of one carbonyl functionality/enzyme subunit, indicating that inactivation is the result of site-specific oxidative modification. Our results suggest that Fe2+ binds to the glucose 6-phosphate binding site and that interaction of the enzyme-bound Fe2+ with H2O2 leads to the oxidative modification of amino acids essential for enzyme activity. Partially inactivated enzyme remained predominantly in the dimeric form, and no change in the apparent affinity of the remaining active subunits for substrate was observed. Partial inactivation did, however, lead to a decrease in the thermal stability of the remaining activity. This decrease in thermal stability could be largely overcome by the addition of glucose 6-phosphate. Thus, although exposure to H2O2 and Fe2+ results in the irreversible inactivation of Glu-6-PDH, the resulting modification is selective, leads to the formation of heterodimers of both active and inactive subunits, and does not appear to cause large scale structural changes. Our results demonstrate the inherent susceptibility of Glu-6-PDH from L. mesenteroides to modification by an oxidation system known to exist in vivo. An assessment of the physiological significance of Fe(2+)-catalyzed oxidation of Glu-6-PDH awaits extension of these studies to mammalian sources known to accumulate less active or inactive forms of the enzyme as a function of age.
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PMID:Iron-catalyzed oxidative modification of glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides. Structural and functional changes. 173 65

Inhibition of glucose-6-phosphate dehydrogenase (G6-PDH) by dithranol (anthralin, CAS 480-22-8) has been studied in the presence of catalase, superoxide dismutase (SOD) and various scavengers of active oxygen species. Most scavengers were found to be either inhibitors of G6-PDH by themselves or simply without effect. The combined addition of catalase and SOD as well as the heat-denatured enzymes and the oxygen radical scavengers alpha-tocopherol and salicylic acid markedly reduced the inhibitory effect of dithranol. The direct exposure of G6-PDH to active oxygen species led to different results. When liberated from a water-soluble naphthalene endoperoxide, singlet oxygen was without effect whereas photosensitization with methylene blue resulted in a total loss of enzyme activity. Experiments under anaerobic conditions revealed that this inhibition was accomplished by the triplet state of the sensitizer. Superoxide anion radical was highly effective at concentrations corresponding to the amount of that produced by a 10 mumol/l dithranol solution. In contrast, hydroxyl, alkylperoxyl and alkoxyl radicals were all less efficient. H2O2 and alkylhydroperoxides did not alter the enzyme activity. The results suggest that .O2- is the potent species towards G6-PDH, if dithranol acts through formation of active oxygen species.
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PMID:Dithranol, glucose-6-phosphate dehydrogenase inhibition and active oxygen species. 181 Feb 65


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