Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An investigation has been made to determine the effectiveness of univalent cations as cofactors for the inductive synthesis of nitrate reductase. In these experiments K(+) functions more effectively as the univalent cation activator than other univalent cations. Substitution of Rb(+) for K(+) resulted in enzyme formation at a rate of about one-half of that obtained with K(+). Sodium, Li(+), or NH(4) (+) either failed to stimulate or completely inhibited the inductive formation of the enzyme. When no univalent cations were present in the induction medium, enzyme formation was delayed for an initial 3-hour period in contrast to the normal one-hour delay in enzyme formation where adequate K(+) was present in the induction medium. During the period of inductive formation of nitrate reductase the activity of pyruvic kinase, a constitutive enzyme, was assayed under conditions where adequate K(+) was present. Results indicate that the presence of the different univalent cations in the induction medium had no striking effect on the activity of this enzyme during the induction period.
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PMID:Effects of univalent cations on the inductive formation of nitrate reductase. 595 44

The effect of tungsten on growth and activity of two molybdoenzymes has been studied in a nitrogen-fixing heterocystous cyanobacterium, Anabaena. Sodium tungstate inhibited growth and inactivated nitrogenase and nitrate reductase. The activity of both enzymes was restored by the addition of molybdenum. Tungstate treatment caused increase in heterocyst frequency both in NO3- medium and in medium free of combined nitrogen. These results suggest that tungstate treatment inactivates the molybdoenzymes in this cyanobacterium.
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PMID:Tungsten-induced inactivation of molybdoenzymes in Anabaena. 676 88

The protective effects of L-cysteine, ascorbic acid, reduced glutathione, L-tryptophan, and sodium pyruvate against UV-B-induced damages were studied in the nitrogen-fixing cyanobacterium, Nostoc muscorum. When added to the culture suspension during UV-B treatment, these chemicals caused a significant protective effect on survival and growth of the organism. Sodium pyruvate conferred the strongest protection whereas the weakest effect was elicited by tryptophan. A 20 min exposure of a culture suspension to UV-B completely inactivated nitrogenase activity but the inactivation was strongly prevented by exogenous addition of ascorbic acid or reduced glutathione during UV-B exposure, and weakly prevented by pyruvate, cysteine and tryptophan. In vivo nitrate reductase activity was not completely lost even after 80 min of UV-B exposure, and addition of the test chemicals did not confer any significant protection to this enzyme. Whereas (14)CO(2) uptake was drastically inhibited (78% inhibition) by 30 min exposure to UV-B in the absence of any test chemical, about 76% activity remained when the UV-B exposure was given to cultures in the presence of ascorbic acid. These results suggest that the damaging effects of UV-B are substantially minimized by certain reducing agents, the protective effect being particularly strong on the O(2) sensitive enzyme, nitrogenase. Presence of these chemicals in their natural habitat or inside the cells of living organisms may partially protect/repair the damaging effects of UV-B radiation.
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PMID:Protective role of certain chemicals against UV-B-induced damage in the nitrogen-fixing cyanobacterium, Nostoc muscorum. 1274 56

Nitrogen stress increases lipids content in microalgae, the main feedstock for algal biodiesel. Sodium tungstate was used in this study to implement nitrogen stress by inhibiting nitrate reductase (NR) in Dunaliella tertiolecta. The reduction of NR activity was accompanied by reduction of chlorophyll and accumulation of lipids. One-stage and two-stage culture strategies were compared. One-stage culture raised total lipids from 18% (control) to 39% (w: w); however, two-stage culture raised lipids to 50% in which neutral lipids were enhanced 2.14 times. To assess the quality of biodiesel produced, fatty acid methyl esters (FAME) composition was studied. It showed a slight variation of unsaturation. In addition, some physical proprieties of biodiesel were estimated and showed that higher heating values were improved by tungstate treatment. In this study, we tried to shed light on some biological impact of NR inhibition in microalgae cells using sodium tungstate which could be exploited in the improvement of biodiesel production.
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PMID:Nitrate Reductase Inhibition Induces Lipid Enhancement of Dunaliella Tertiolecta for Biodiesel Production. 3062 43

Nitrate is one of the major sources of nitrogen for the growth of plants. It is taken up by plant roots and transported to the leaves where it is reduced to nitrite in the. The main objective of this research was to investigate stimulatory effects of sodium nitrate, potassium nitrate, ammonia and urea on the production/generation of the nitrate reductase mRNA in Triticum aestivum plants. The plants were grown in standard nutrient solution for 21 days and then starved in a media without nitrate for seven days. Starved plants were stimulated with various concentrations of sodium nitrate, potassium nitrate, ammonia and urea, and the expression of nitrate reductase mRNA was analyzed by real-time PCR. Our results indicated that starvation caused significant decrease in the production of nitrate reductase mRNA in the plant leaf. Sodium and potassium nitrate were capable of restoring the production of nitrate mRNA in a dose-dependent manner, since 50 mM of each produced the highest level of the mRNA. The stimulatory effect of potassium nitrate was higher than sodium nitrate, while ammonia and urea did not show such activity. At low concentrations, sodium nitrate and potassium nitrate caused significant increase in the nitrate/nitrite mRNA production, whereas high concentrations of these salts suppressed the expression of this gene considerably.
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PMID:Analysis of nitrate reductase mRNA expression and nitrate reductase activity in response to nitrogen supply. 3080 76