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)

Physiological alterations and regulation of heterocyst and nitrogenase formation have been studied in Het(-) Fix(-) mutant strain of diazotrophic cyanobacterium Anabaena variabilis. Het(-) Fix(-) mutant strain of A. variabilis has been isolated by N-methyl-N'-nitro-N"-nitrosoguanidine (NTG) mutagenesis and was screened with the penicillin enrichment (500 microg ml(-1)). Growth, heterocyst differentiation, nitrogenase and glutamine synthetase (biosynthetic and transferase), (14)CO(2)-fixation, nitrate reductase (NR), nitrite reductase (NiR), glucose-6-phosphate dehydrogenase (G6PDH), and isocitrate dehydrogenase (IDH) activities, and NO(3)(-), NO(2)(-), and NH(4)(+) uptake and whole cell protein profile in different metabolic conditions were studied in the Het(-) Fix(-) mutant strain taking wild-type A. variabilis as reference. Het(-) Fix(-) mutant strain was incapable of assimilating elemental nitrogen (N(2)) due to its inability to form heterocysts and nitrogenase and this was the reason for its inability to grow in BG-11(0) medium (free from combined nitrogen). In contrast, wild-type strain grew reasonably well in the absence of combined nitrogen sources and also showed heterocyst differentiation (8.5%) and nitrogenase activity (10.8 etamol C(2)H(4) formed microg(-1) Chl a h(-1)) in N(2)-medium. Wild-type strain also exhibited higher NR, NiR, and GS activities compared to its Het(-) Fix(-) mutant strain, which may presumably be due to acquisition of high uptake of NO(3)(-), NO(2)(-), and NH(2)(+). Wild-type strain in contrast to its Het(-) Fix(-) mutant strain also exhibited high level of G6PDH, IDH, and (14)CO(2) fixation activities. Low levels of G6PDH and IDH activities in Het(-) Fix(-) mutant strain further confirmed the lack of heterocyst differentiation and nitrogenase activity in the Het(-) Fix(-) mutant strain.NR, NiR, and GS activities in both the strains were energy-dependent and the energy required is mainly derived from photophosphorylation. Furthermore, it was found that de novo protein synthesis is necessarily required for the activities of NR, NiR, and GS in both wild-type and its Het(-) Fix(-) mutant strain.
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PMID:Physiological alterations and regulation of heterocyst and nitrogenase formation in Het(-) Fix(-) mutant strain of Anabaena variabilis. 1223 60

Various inorganic and organic nitrogen sources were used to compare their effects on the lipogenesis and the activities of lipogenic enzymes (providing acetyl-CoA and donating NADPH) in gamma-linolenic acid-producing fungus Cunninghamella echinulata. Lipid accumulation was enhanced by organic nitrogen, among them the presence of corn-steep led to almost 40% oil in the biomass. While organic nitrogen increased activities of acetyl-CoA carboxylase (ACC) and malic enzyme (ME), ATP:citrate lyase (ACL) was rapidly enhanced by ammonium ion. The use of NaNO(3) resulted in high activities of glucose 6-phosphate dehydrogenase (GPD) and 6-phosphogluconate dehydrogenase (PGD). NADP-isocitrate dehydrogenase (NADP-ICD) was more active when the fungus utilized all inorganic N-compounds. The rise of nitrogen concentration in medium was accompanied with reduced lipid accumulation and a fall of ACL, ACC, and ME. In contrast, N-sufficient conditions favored biomass growth and elevated activities of GPD and PGD. Kinetic experiments also suggest that a significant portion of the required acetyl-CoA was being provided via ACL and ACC, and ME (probably coupled with GPD) channeled the NADPH into the fatty acid biosynthesis. The contribution of the lipogenic enzymes to metabolic pathways other than lipogenesis is also discussed.
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PMID:Effect of nitrogen sources on the activities of lipogenic enzymes in oleaginous fungus Cunninghamella echinulata. 1250 58

We used a carrot (Daucus carota L. cv. Saint Valery) cell suspension culture as a simplified model system to study the effects of the allelochemical compound coumarin (1,2 benzopyrone) on cell growth and utilisation of exogenous nitrate, ammonium and carbohydrates. Exposure to micromolar levels of coumarin caused severe inhibition of cell growth starting from the second day of culture onwards. At the same time, the presence of 50 mumol/L coumarin caused accumulation of free amino acids and of ammonium in the cultured cells, and stimulated their glutamine synthetase, glutamate dehydrogenase, glucose-6-phosphate dehydrogenase and phosphoenolpyruvate carboxylase activities. Malate dehydrogenase, on the other hand, was inhibited under the same conditions. These effects were interpreted in terms of the stimulation of protein catabolism and/or interference with protein biosynthesis induced by coumarin. This could have led to a series of compensatory changes in the activities of enzymes linking nitrogen and carbon metabolism. Because coumarin seemed to abolish the exponential phase and to accelerate the onset of the stationary phase of cell growth, we hypothesise that such allelochemical compounds may act in nature as an inhibitor of the cell cycle and/or as a senescence-promoting substance.
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PMID:Coumarin inhibits the growth of carrot (Daucus carota L. cv. Saint Valery) cells in suspension culture. 1274 79

Wright, D. N. (Iowa State University, Ames), and W. R. Lockhart. Effects of growth rate and limiting substrate on glucose metabolism in Escherichia coli. J. Bacteriol. 89:1082-1085. 1965.-Escherichia coli was grown in continuous culture at various rates in a defined medium with either glucose of (NH(4))(2)SO(4) as the rate-limiting substrate. Cellular content of polysaccharide ("glycogen") is greater in cells grown under nitrogen limitation with glucose available in excess, and is greater in rapidly grown than in slowly grown cells. The ability of cells to carry on endogenous respiration, as measured by tetrazolium reduction, can be correlated with their glycogen content. In carbon-limited cultures, the proportion of substrate glucose diverted to glycogen production is least for cells grown slowly, which may reflect greater energy requirements for cell maintenance in such cultures. The activity of glucose-6-phosphate dehydrogenase (indicating function of a C-1 preferential pathway for glucose degradation) is greater in rapidly grown cells, confirming earlier observations in batch cultures. Activity of this enzyme is also greater in nitrogen-limited than in carbon-limited cells, suggesting that there may be catabolic repression of the Embden-Meyerhoff pathway when glucose is available in excess.
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PMID:EFFECTS OF GROWTH RATE AND LIMITING SUBSTRATE ON GLUCOSE METABOLISM IN ESCHERICHIA COLI. 1427 99

Rubber tire material contains toxic compounds including oils rich in polycyclic aromatic hydrocarbons (PAH), so-called highly aromatic (HA) oils, as well as other reactive additives used as antioxidants, antiozonants, and vulcanization accelerators. The toxicity of rubber tire leachates to aquatic organisms has been demonstrated before. However, previous studies have focused on lethal rather than sublethal effects. We kept rainbow trout (Oncorhynchus mykiss) in tanks with two types of tires: a tire containing HA oils in the tread or a tire free of HA oils in the tread. After 1 d of exposure, an induction of cytochrome P4501A1 (CYP1A1) was evident in both exposed groups, measured as elevated ethoxyresorufin-O-deethylase (EROD) activity and increased CYP1A1 mRNA levels. After two weeks of exposure, EROD activity and CYP1A1 mRNA were still high in fish exposed to leachate from HA oil-containing tire, whereas the effect was somewhat lower in fish exposed to leachate from HA oil-free tread tire. Compounds in the tire leachates also affected antioxidant parameters. Total glutathione concentration in liver as well as hepatic glutathione reductase, glutathione S-transferase, and glucose-6-phosphate dehydrogenase activities were markedly elevated after two weeks of exposure in both groups. The responses were greater in the group exposed to leachate from HA oil-free tread tire. Vitellogenin measurements did not indicate leakage of estrogenic compounds from the tires. Chemical analyses of bile from exposed fish revealed the presence of hydroxylated PAH as well as aromatic nitrogen compounds indicating uptake of these compounds by the fish.
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PMID:Biomarker responses and chemical analyses in fish indicate leakage of polycyclic aromatic hydrocarbons and other compounds from car tire rubber. 1471 32

Vitrification, is the most promising option for the cryopreservation of fish embryos but requires high concentrations of potentially toxic cryoprotectants. In this study, embryos from Turbot and Zebrafish, each in two developmental stages, were submitted to a four stepwise cryoprotectant incorporation protocol. After incubation in the vitrificant solution (5M dimethyl sulfoxide, 2M methanol, 1M ethylen-glycol and 10% sucrose) embryos were loaded in straws and plunged into liquid nitrogen. The activity of two cytoplasmic enzymes, LDH and G6PDH, and the hatching rates were analyzed in control embryos, those subjected to the cryoprotectant solutions and in frozen/thawed embryos. Results showed that the cryoprotectants incorporation protocol did not have important effects on the analyzed enzymatic activities, which remained at similar levels to that in control embryos but significantly reduced the hatching rates. Turbot was less sensitive than Zebrafish to the toxic effect of the cryoprotectants, achieving hatching rates of 74.8% in comparison with fresh control embryos at G stage, whereas in Zebrafish only 17.7% of hatching was reported with five somites-treated embryos. In Turbot, G stage was more resistant to the cryoprotectants and thus more convenient for further vitrification studies. After vitrification no survival was recorded and enzymatic activities dropped significantly, particularly in Zebrafish, indicating cell damage and loss of cytoplasmic enzymes. Nevertheless, total cell lysis was not produced, and once again Turbot was more resistant to the effect of vitrification, particularly at the later stage. In that stage, Turbot embryos showed around 50% of G6PDH activity after vitrification, in comparison with the control, indicating the preservation of some cellular activity after freezing-thawing, despite the loss of developmental ability.
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PMID:Effect of a vitrification protocol on the lactate dehydrogenase and glucose-6-phosphate dehydrogenase activities and the hatching rates of Zebrafish (Danio rerio) and Turbot (Scophthalmus maximus) embryos. 1503 69

Following brain inflammatory stimuli, astrocytes actively synthesize nitric oxide and peroxynitrite. These nitrogen-derived species trigger a repertoire of biochemical effects, including alteration of mitochondrial function and redox status both in astrocytes and neighboring neurons. Furthermore, under such nitrosative stress astrocytes show remarkable resistance in spite of having their mitochondria impaired, whereas the neighboring neurons show vulnerability. In this review, we discuss recent evidence strongly suggesting that nitrogen-derived species modulate key regulatory steps of glucose metabolism. These involve up-regulation of high-affinity glucose transporter, stimulation of glycolysis at 6-phosphofructo-1-kinase, and activation of pentose-phosphate pathway at glucose-6-phosphate dehydrogenase. We conclude that the orchestrated stimulation of glucose-metabolising pathways by nitric oxide would be a transient attempt of certain neural cells to compensate for the impaired energy status and oxidised glutathione and thus emerge from an otherwise neuropathological outcome.
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PMID:Regulation of glucose metabolism by nitrosative stress in neural cells. 1505 17

Ferric nitrilotriacetate (Fe-NTA) is a known potent nephrotoxic agent. In this communication, we report the chemopreventive effect of soy isoflavones on renal oxidative stress, toxicity and cell proliferation response in Wistar rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) enhances gamma-glutamyl transpeptidase, renal lipid peroxidation, xanthine oxidase and hydrogen peroxide (H2O2) generation with reduction in renal glutathione content, antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase. Fe-NTA treatment also induced tumor promotion markers, viz., ornithine decarboxylase (ODC) activity and thymidine [3H] incorporation into renal DNA. A sharp elevation in the levels of blood urea nitrogen and serum creatinine has also been observed. Treatment of rats orally with soy isoflavones (5 mg/kg body weight and 10 mg/kg body weight) resulted in significant decreases in gamma-glutamyl transpeptidase, lipid peroxidation, xanthine oxidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). Renal glutathione content (P < 0.01), glutathione metabolizing enzymes (P < 0.001) and antioxidant enzymes were also returned to normal levels (P < 0.001). Thus, our data suggest that soy isoflavones may be used as an effective chemopreventive agent against Fe-NTA-mediated renal oxidative stress, toxicity and cell proliferation response in Wistar rats.
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PMID:Induction of renal oxidative stress and cell proliferation response by ferric nitrilotriacetate (Fe-NTA): diminution by soy isoflavones. 1529 41

Potassium bromate (KBrO3) is a potent nephrotoxic agent. In this study, we show the modulatory effect of soy isoflavones on KBrO3-mediated renal oxidative stress and subsequent cell proliferation response in Wistar rats. KBrO3 (125 mg/kg body weight, intraperitoneally) caused reduction in renal glutathione content, activities of renal anti-oxidant enzymes, viz., glutathione peroxidase, glutathione reductase, catalase, glucose-6-phosphate dehydrogenase and phase-II metabolising enzymes such as glutathione-S-transferase and quinone reductase with enhancement in xanthine oxidase, lipid peroxidation, gamma-glutamyl transpeptidase and hydrogen peroxide (H2O2). KBrO3 treatment also induced blood urea nitrogen, serum creatinine and tumor promotion markers, viz., ornithine decarboxylase (ODC) activity and thymidine [3H] incorporation into renal DNA. Treatment of rats orally with soy isoflavones (5 mg/kg body weight and 10 mg/kg body weight) resulted in a significant decrease in xanthine oxidase (P < 0.05), lipid peroxidation, gamma-glutamyl transpeptidase, H2O2 generation, blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). There was also significant recovery of renal glutathione content (P < 0.01), anti-oxidant enzymes and phase-II metabolising enzymes (P < 0.001). Thus, our results show that soy isoflavones acts as potent chemopreventive agent against KBrO3-mediated renal oxidative stress, toxicity and subsequent cell proliferation response in Wistar rats.
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PMID:Abrogation of potassium bromate-induced renal oxidative stress and subsequent cell proliferation response by soy isoflavones in Wistar rats. 1529 31

In barley (Hordeum vulgare L. var. Nure), glutamate synthesis and the production of reducing power by the oxidative pentose phosphate pathway (OPPP) are strictly correlated biochemical processes. NADH-GOGAT was the major root isoform, whose activity increased on a medium supplied with NH4+ or NO3-; by contrast, no noticeable variations could be observed in the leaves of plants supplied with nitrogen. In the leaves, the major isoform is Fd-GOGAT, whose activity increased under nitrogen feeding. G6PDH activity increased in the roots supplied with nitrogen; no variations were observed in the leaves. Moreover, an increase of the P2 isoform in the roots was measured, giving 13.6% G6PDH activity localized in the plastids under ammonium, and 25.2% under nitrate feeding conditions. Western blots confirmed that P2-G6PDH protein was induced in the roots by nitrogen. P1-G6PDH protein was absent in the roots and increased in the leaves by nitrogen supply to the plants. The changes measured in cytosolic G6PDH seem correlated to more general cell growth processes, and do not appear to be directly involved in glutamate synthesis. The effects of light on Fd-GOGAT is discussed, together with the possibility for P2-G6PDH to sustain nitrogen assimilation upon illumination.
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PMID:Glutamate synthase activities and protein changes in relation to nitrogen nutrition in barley: the dependence on different plastidic glucose-6P dehydrogenase isoforms. 1550 8


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