Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Nitrate reductase of the salt-tolerant alga Dunaliella parva could utilize NADPH as well as NADH as an electron donor. The two pyridine nucleotide-dependent activities could not be separated by either ion exchange chromatography on DEAE-cellulose or gel filtration on Sepharose 4B. The NADPH-dependent activity was not inhibited by phosphatase inhibitors. NADPH was not hydrolyzed to NADH and inorganic phosphate in the course of nitrate reduction. Reduction of nitrate in vitro could be coupled to a NADPH-regenerating system of glycerol and NADP-dependent glycerol dehydrogenase. It is concluded that the nitrate reductase of D. parva will function with NADPH as well as NADH. This is a unique characteristic not common to most algae.
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PMID:Specificity for Nicotinamide Adenine Dinucleotide and Nicotinamide Adenine Dinucleotide Phosphate of Nitrate Reductase from the Salt-tolerant Alga Dunaliella parva. 1665 20

By use of affinity chromatography on blue dextran-Sepharose, two nitrate reductases from rice (Oryza sativa L.) seedlings, specifically, NADH:nitrate oxidoreductase (EC 1.6.6.1) and NAD(P)-H:nitrate oxidoreductase (EC 1.6.6.2), have been partially separated. Nitrate-induced seedlings contained more NADH-nitrate reductase than NAD(P)H-nitrate reductase, whereas chloramphenicol-induced seedlings contained primarily NAD(P)H-nitrate reductase. NAD(P)H-nitrate reductase was shown to utilize NADPH directly as reductant. This enzyme has a preference for NADPH, but reacts about half as well with NADH.
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PMID:NADH- and NAD(P)H-Nitrate Reductases in Rice Seedlings. 1665 65

The objective of this experiment was to elucidate the manner in which N metabolism is influenced by S nutrition. Maize (Zea mays L.) seedlings supplied with Hoagland solution minus SO(4) (2-) exhibited S deficiency symptoms 12 days after emergence. Prior to development of these symptoms, a decline in leaf blade nitrate reductase (NR, EC 1.6.6.1) activity was observed in S-deprived seedlings compared to normal seedlings. Twelve days after emergence, in vitro NR activity was diminished 50% compared to normal seedlings. Glutamine synthetase (EC 6.3.1.2) and NAD-glutamate dehydrogenase (EC 1.4.1.2) activities were less severely affected (19 and 13%, respectively, at day 12). NADP-glutamate dehydrogenase (EC 1.4.1.4) activity and leaf blade fresh weight were not altered by S deprivation. Concentrations of soluble protein and chlorophyll (a and b) in leaf blades were reduced 18 and 25%, respectively, at day 12. A significantly higher concentration of NO(3) (-)-N was observed for leaf blade and stem (culms, leaf sheaths, and unfurled leaves) fractions (46 and 31%, respectively) in S-deprived plants. In contrast to the other parameters measured, NR activity in S-deprived seedlings could be readily restored to the normal level by addition of SO(4) (2-). The apparent preferential effect of S deprivation on NR activity could be causally related to the observed changes in NO(3) (-)-N and soluble protein concentration.
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PMID:Sulfur deprivation and nitrogen metabolism in maize seedlings. 1666 Apr 22

The localization of enzymes responsible for nitrate assimilation and the generation of NADH for nitrate reduction were studied in corn (Zea mays L.) leaf blades. The techniques used effectively separated mesophyll and bundle sheath cells as judged by microscopic observations, enzymic assays, chlorophyll a/b ratios and photochemical activities. Nitrate reductase, nitrite reductase, and the nitrate content of leaf blades were localized primarily in the mesophyll cells, although some nitrite reductase was found in the bundle sheath cells. Glutamine synthetase, NAD-malate dehydrogenase, NAD-glyceraldehyde-3-phosphate dehydrogenase, and NADP-glutamate dehydrogenase were found in both types of cells, however, more NADP-glutamate dehydrogenase was found in the bundle sheath cells than in the mesophyll cells. These data indicate that the mesophyll cells are the major site for nitrate assimilation in the leaf blade because they contained an ample supply of nitrate and the enzymes considered essential for the assimilation of nitrate into amino acids. Because the specific activity of nitrate reductase was severalfold lower than the other enzymes involved in nitrate assimilation, nitrate reduction is indicated as the rate-limiting step in situ. A sequence of reactions is proposed for nitrate assimilation in the mesophyll cells of corn leaves as related to the C-4 pathway of photosynthesis.
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PMID:Pathway for Nitrate Assimilation in Corn (Zea mays L.) Leaves: Cellular Distribution of Enzymes and Energy Sources for Nitrate Reduction. 1666 May 71

After x-ray irradiation, 13 mutants of Chlorella sorokiniana incapable of using NO(3) (-) as N source were isolated using a pinpoint method. Using immunoprecipitation and Western blot assays, no nitrate reductase was found in five strains while in eight mutants the enzyme was detected. The latter strains contained different patterns of nitrate reductase partial reactions. All isolates were of the nia-type as indicated by the inducibility of purine hydroxylase I and by complementation of nitrate reductase activity in the Neurospora crassa mutant Nit-1. A restoration of NADP-nitrate reductase in Nit-1 was also obtained with NH(4) (+)-grown cells indicating that Mo-cofactor is constitutive in Chlorella. Complementation experiments among the Chlorella mutants resulted in restoration of NADH-nitrate reductase activity. The characteristics of some of the Chlorella mutants are discussed in view of an improper orientation of Mo-cofactor in the residual nitrate reductase protein.
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PMID:Characterization of Nitrate Reductase Deficient Mutants of Chlorella sorokiniana. 1666 22

cDNA clones were selected from a corn (Zea mays L.) leaf lambda gt11 expression library using polyclonal antibodies for corn leaf NADH:nitrate reductase. One clone, Zmnrl, had a 2.1 kilobase insert, which hybridized to a 3.2 kilobase mRNA. The deduced amino acid sequence of Zmnrl was nearly identical to peptide sequences of corn leaf NADH:nitrate reductase. Another clone, Zm6, had an insert of 1.4 kilobase, which hybridized to a 1.4 kilobase mRNA, and its sequence coded for chloroplastic NAD(P)(+):glyceraldehyde-3-phosphate dehydrogenase based on comparisons to sequences of this enzyme from tobacco and corn. When nitrate was supplied to N-starved, etiolated corn plants, nitrate reductase, and glyceraldehyde-3-phosphate dehydrogenase mRNA levels in leaves increased in parallel. When green leaves were treated with nitrate, only nitrate reductase mRNA levels were increased. Nitrate is a specific inducer of nitrate reductase in green leaves, but appears to have a more general effect in etiolated leaves. In the dark, nitrate induced nitrate reductase expression in both etiolated and green leaves, indicating light and functional chloroplast were not required for enzyme expression.
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PMID:cDNA Clones for Corn Leaf NADH:Nitrate Reductase and Chloroplast NAD(P):Glyceraldehyde-3-Phosphate Dehydrogenase : Characterization of the Clones and Analysis of the Expression of the Genes in Leaves as Influenced by Nitrate in the Light and Dark. 1666 79

Ecdysterone (100 ng/100 g) chronic oral administration (2 months after STZ (5 mg/100 g) administration) normalized plasma glucose levels in rats. This potent hypoglycemic effect of ecdysterone depend on inhibition of non-constitutive NO synthesis by Ca(2+)-independent iNOS and NADP-dependent nitrate reductase as well as inhibition of L-arginine degradation by arginase result in up-regulation of Ca(2+)-dependent constitutive NO synthesis by eNOS or mithochondrial nNOS in heart and aorta of rats.
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PMID:[NO-dependent mechanisms of ecdysterone protective action on the heart and vessels in streptozotocin-induced diabetes mellitus in rats]. 1772 37

Thirty-five patients with community-acquired pneumonia were examined. Studies of red blood cells and expired air condensate revealed significant nitric oxide metabolic disturbances in them. In a group of 17 patients, the use of N-acetylcysteine in the complex therapy resulted in the normalization of most parameters that characterized nitric oxide metabolism (nitrates, nitrites, peroxynitrite, NADP-H-diaphorase, and nitrate reductase activity). The positive changes were less significant in the control group receiving mucaltin instead of N-acetylcysteine. The established regularities in the balance change of nitric oxide metabolism in blood and expired air condensate at the height of the disease and positive changes during therapy including N-acetylcysteine suggest that nitric oxide plays an important role in the pathogenesis of community-acquired pneumonia.
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PMID:[Nitric oxide metabolism in the inclusion of N-acetylcysteine into the complex therapy of patients with community-acquired pneumonia]. 1803 1

Nutrient enrichment with a nitrogen (as nitrate) or carbon (as fructose) source to unaerated diazo and photoautorophic cultures of the cyanobacterium Anabaena torulosa induced early development of akinetes with high frequency. When cultures under any mode of nutrition were aerated, akinetes were not differentiated. Unaerated cultures with nitrate nitrogen or fructose exhibited higher respiratory rates and nitrogen assimilation compared to aerated cultures. This was evidenced by increased respiratory O2 uptake and high activities of pyruvate kinase, malate dehydrogenase (NAD+), nitrogenase and nitrate reductase signifying that akinete forming unaerated cultures exhibited high carbon dissimilation and nitrogen assimilation resulting in high nitrogenous build up in the cells. Aerated, non-akinete cultures, on the other hand, were associated with low respiratory O2 uptake, low pyruvate kinase and malate dehydrogenase (NAD+) activities, suggesting that carbon dissimilation was not favoured either in presence of nitrate or fructose. Moreover, higher activity of NADP+ linked malate dehydrogenase and lower nitrate reductase activity in aerated cultures led to a high carbon and low nitrogen content of the cells resulting in high cellular C:N ratio. The results suggest that interaction between carbon and nitrogen metabolism regulates akinete development in A. torulosa.
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PMID:Interaction between carbon and nitrogen metabolism during akinete development in the cyanobacterium Anabaena torulosa. 1838 24

We investigated the role of glutamine synthetases (cytosolic GS1 and chloroplast GS2) and glutamate synthases (ferredoxin-GOGAT and NADH-GOGAT) in the inorganic nitrogen assimilation and reassimilation into amino acids between bundle sheath cells and mesophyll cells for the remobilization of amino acids during the early phase of grain filling in Zea mays L. The plants responded to a light/dark cycle at the level of nitrate, ammonium and amino acids in the second leaf, upward from the primary ear, which acted as the source organ. The assimilation of ammonium issued from distinct pathways and amino acid synthesis were evaluated from the diurnal rhythms of the transcripts and the encoded enzyme activities of nitrate reductase, nitrite reductase, GS1, GS2, ferredoxin-GOGAT, NADH-GOGAT, NADH-glutamate dehydrogenase and asparagine synthetase. We discerned the specific role of the isoproteins of ferredoxin and ferredoxin:NADP(+) oxidoreductase in providing ferredoxin-GOGAT with photoreduced or enzymatically reduced ferredoxin as the electron donor. The spatial distribution of ferredoxin-GOGAT supported its role in the nitrogen (re)assimilation and reallocation in bundle sheath cells and mesophyll cells of the source leaf. The diurnal nitrogen recycling within the plants took place via the specific amino acids in the phloem and xylem exudates. Taken together, we conclude that the GS1/ferredoxin-GOGAT cycle is the main pathway of inorganic nitrogen assimilation and recycling into glutamine and glutamate, and preconditions amino acid interconversion and remobilization.
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PMID:Implication of the glutamine synthetase/glutamate synthase pathway in conditioning the amino acid metabolism in bundle sheath and mesophyll cells of maize leaves. 1847 60


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