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:1.7.1.1 (nitrate reductase)
3,728 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The properties of 279 Ps. aeruginosa strains were studied in 70 tests. The use of a synthetic peptone-free mineral medium for the determination of sugar oxidation was shown to have advantages over the use of liquid Giess' media. Ps. aeruginosa cultures isolated from human patients, animals, soil and water were characterized by a number of common signs, irrespective of their origin. The strains isolated from human patients were resistant practically to all antibiotics widely used in clinical practice; the cultures isolated from soil and water retained their sensitivity to antibiotics; the strains isolated from animals retained sensitivity to some antibiotics. To identify Ps. aeruginosa in practical bacteriological laboratories, the following parameters should be determined: mobility; the character of growth in Levine's and Ploskirev's media; ability to grow at 42 degrees C and 4 degrees C; the fermentation of carbohydrates in Olkenitsky's medium and their oxidation in a mineral medium; indole and hydroxide sulfide production; the methyl red and Voges--Proskauer reaction; the presence of pigments, oxidase, catalase, gelatinase, nitrate reductase and arginine dehydrolase, urease; resistance to antibiotics.
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PMID:[Morphologic, cultural, and biochemical properties of cultures of Pseudomonas aeruginosa isolated from patients, animals, and the environment]. 679 19

Gel chromatography experiments over a wide range of protein concentrations showed that Chlorella nitrate reductase is a nonassociating protein with a Stokes radius of 81 A. Sedimentation equilibrium of nitrate reductase in H2O-D2O solvents yielded a partial specific volume of 0.800 +/- 0.014 (n = 12) and a Mr = 360,000 +/- 25,000. No lipid was found associated with nitrate reductase. Cross-linking with the bifunctional reagent, dimethyl suberimidate, and subsequent separation of products by sodium dodecyl sulfate-polyacrylamide gel electrophoresis yielded four protein-staining bands in which the molecular weights of the cross-linked products were integral multiples of the monomeric molecular weight (90,000). Extensive cross-linking of the enzyme resulted in one principal protein-staining band of 360,000, corresponding to a tetramer. The cross-linked tetramer of nitrate reductase appeared to have identical physical properties as the native enzyme. The cross-linking pattern produced by reaction with dimethyl suberimidate suggested that nitrate reductase is an isologous tetramer which has at least two different types of bonding domains. Gel filtration, sedimentation equilibrium, and density gradient experiments at very low enzyme concentrations indicated that nitrate reductase dissociates to a species with a Stokes radius of 54 A, s20.w of 7.1, and Mr = approximately 200,000 at these low enzyme concentrations. No change in specific activity of the enzyme was observed over this concentration range. Treatment of nitrate reductase with trypsin or with cyanogen bromide yielded the number of peptides expected for identical subunits. From these results, it is concluded that Chlorella nitrate reductase is a homotetramer with dihedral symmetry ("dimer of dimers").
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PMID:Quaternary structure of assimilatory NADH:nitrate reductase from Chlorella. 720 4

The effect on various caecal bacteria and their metabolic activities of feeding diet containing transgalactosylated oligosaccharides (TOS) with or without Bifidobacterium breve (administered in the drinking water) was investigated in rats colonized with a human faecal microflora. TOS (5% w/w in diet) or TOS plus B. breve, given for 4 weeks, induced increases in caecal concentration of total anaerobic bacteria, lactobacilli and bifidobacteria, and decreases in numbers of enterobacteria. Caecal pH was significantly reduced by feeding TOS, as were the activities of beta-glucuronidase and nitrate reductase. In contrast, beta-glucosidase activity was increased in TOS-fed rats. Dietary TOS was also associated with decreased conversion, by caecal contents, of the dietary carcinogen 2-amino-3-methyl-3H-imidazo[4,5-f] quinoline (IQ) to its genotoxic 7-hydroxy derivative.
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PMID:The effects of transgalactosylated oligosaccharides on gut flora metabolism in rats associated with a human faecal microflora. 834 28

The Paracoccus denitrificans fnrP gene encoding a homologue of the Escherichia coli FNR protein was localized upstream of the gene cluster that encodes the high-affinity cbb3-type oxidase. FnrP harbours the invariant cysteine residues that are supposed to be the ligands of the redox-sensitive [4Fe-4S] cluster in FNR. NNR, another FNR-like transcriptional regulator in P. denitrificans, does not. Analysis of FnrP and NNR single and double mutants revealed that the two regulators each exert exclusive control on the expression of a discrete set of target genes. In FnrP mutants, the expression of cytochrome c peroxidase was blocked, that of membrane-bound nitrate reductase and the cbb3-type oxidase was significantly reduced, whilst the activity of the bb3-type quinol oxidase was increased. The amounts of the nitrite and nitric oxide reductases in these FnrP mutants were the same as in the wild type. NNR mutants, on the other hand, were disturbed exclusively in the concentrations of nitrite reductase and nitric oxide reductase. An FnrP.NNR double mutant combined the phenotypes of the single mutant strains. In all three mutants, the concentrations and/or activities of the aa3-type oxidase, cytochrome C550, cytochrome C552, and nitrous oxide reductase equalled those in the wild type. As the FNR boxes in front of the FnrP- and NNR-regulated genes are highly similar to or even identical to each other, the absence of cross-talk between the regulation by FnrP and NNR implies that as yet unidentified factors are important in the control. It is proposed that the redox state of an intracellular redox couple other than the oxygen/water couple is one of the factors that modulates the activity of FnrP.
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PMID:FnrP and NNR of Paracoccus denitrificans are both members of the FNR family of transcriptional activators but have distinct roles in respiratory adaptation in response to oxygen limitation. 907 27

A plasmid-borne transcriptional fusion between the Escherichia coli nitrate reductase (narG) promoter and the Photorhabdus luminescens lux operon provides E. coli with a highly bioluminescent phenotype in the presence of nitrate. This E. coli biosensor can detect nitrate to a level of 5 x 10(-5) mol l-1 (0.3 ppm), levels relevant to those levels encountered in brewing water. Since induction of the narG promoter requires NarL, the plasmid-based sensor can also be used to interrogate enteric bacteria for the presence of functional homologues of this E. coli regulatory protein. Obesumbacterium proteus, an important bacterial brewery contaminant, failed to provide nitrate-dependent bioluminescence demonstrating divergence in this organism from E. coli in the mechanism of nitrate reductase regulation.
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PMID:The construction and application of a lux-based nitrate biosensor. 917 42

An obligately methylotrophic organism was isolated from a water well that manifested symptoms of biofouling. The isolate was appendaged and utilized methylamine, dimethylamine, trimethylamine, or methanol as the sole carbon and energy source. The isolate exhibited hydroxypyruvate reductase activity, suggesting C1-assimilation via the serine pathway. Fatty acid profiling indicated the predominance of 18:1 cis-fatty acids. The isolate did not grow anaerobically with nitrate as the final electron acceptor. Genomic DNA from the isolate did not hybridize against the narG gene, which encodes the alpha subunit of dissimilatory nitrate reductase in Escherichia coli. The phenotypic data suggested the assignment of the isolate to the genus Hyphomicrobium. The identification was supported by phylogenetic characterization based on 16S rRNA sequence comparisons of the isolate.
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PMID:Phylogenetic and narG analysis of a Hyphomicrobium isolate. 929 67

A water soluble truncated heme domain (a tetramer of MW = 45 kDa) of the tetrameric nitrate reductase complex from the green alga Chlorella vulgaris has been overexpressed and purified. This truncated heme domain with four identical subunits has a high redox potential (midpoint potential E1/2 = +16 mV) as compared with other heme-containing flavoproteins. We have undertaken a determination of the detailed configuration of the heme moiety in order to understand the unique electrochemical property of the heme moiety of this enzyme. We report here the study of the heme prosthetic group of the truncated heme domain by the use of 2D 1H and 13C NMR techniques. A complete signal assignment of the heme has been achieved. Our observations suggest that the heme configuration is similar to that of the crystal structure of the membrane-bound bovine liver cytochrome b5.
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PMID:1H and 13C NMR studies of a truncated heme domain from Chlorella vulgaris nitrate reductase: signal assignment of the heme moiety. 950 89

The construction and characterization of a nitrate reductase-based amperometric electrode for determination of nitrate ion is described. The electrode consisted of nitrate reductase held by dialysis membrane onto a Nafion-coated glassy carbon electrode. Methyl viologen was allowed to absorb into the Nafion layer, which acted as a reservoir for the electron mediator. The utility of the electrode to assay fertilizer and water sample for nitrate was demonstrated. The assays conducted with this electrode compared well with colorimetric and potentiometric assays of the same samples.
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PMID:Construction and characterization of nitrate reductase-based amperometric electrode and nitrate assay of fertilizers and drinking water. 956 60

Maize (Zea mays L.) plants were grown to the nine-leaf stage. Despite a saturating N supply, the youngest mature leaves (seventh position on the stem) contained little NO3- reserve. Droughted plants (deprived of nutrient solution) showed changes in foliar enzyme activities, mRNA accumulation, photosynthesis, and carbohydrate and amino acid contents. Total leaf water potential and CO2 assimilation rates, measured 3 h into the photoperiod, decreased 3 d after the onset of drought. Starch, glucose, fructose, and amino acids, but not sucrose (Suc), accumulated in the leaves of droughted plants. Maximal extractable phosphoenolpyruvate carboxylase activities increased slightly during water deficit, whereas the sensitivity of this enzyme to the inhibitor malate decreased. Maximal extractable Suc phosphate synthase activities decreased as a result of water stress, and there was an increase in the sensitivity to the inhibitor orthophosphate. A correlation between maximal extractable foliar nitrate reductase (NR) activity and the rate of CO2 assimilation was observed. The NR activation state and maximal extractable NR activity declined rapidly in response to drought. Photosynthesis and NR activity recovered rapidly when nutrient solution was restored at this point. The decrease in maximal extractable NR activity was accompanied by a decrease in NR transcripts, whereas Suc phosphate synthase and phosphoenolpyruvate carboxylase mRNAs were much less affected. The coordination of N and C metabolism is retained during drought conditions via modulation of the activities of Suc phosphate synthase and NR commensurate with the prevailing rate of photosynthesis.
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PMID:Drought-induced effects on nitrate reductase activity and mRNA and on the coordination of nitrogen and carbon metabolism in maize leaves 957 98

Transformed (cauliflower mosaic virus 35S promoter [35S]) tobacco (Nicotiana plumbaginifolia L.) plants constitutively expressing nitrate reductase (NR) and untransformed controls were subjected to drought for 5 d. Drought-induced changes in biomass accumulation and photosynthesis were comparable in both lines of plants. After 4 d of water deprivation, a large increase in the ratio of shoot dry weight to fresh weight was observed, together with a decrease in the rate of photosynthetic CO2 assimilation. Foliar sucrose increased in both lines during water stress, but hexoses increased only in leaves from untransformed controls. Foliar NO3- decreased rapidly in both lines and was halved within 2 d of the onset of water deprivation. Total foliar amino acids decreased in leaves of both lines following water deprivation. After 4 d of water deprivation no NR activity could be detected in leaves of untransformed plants, whereas about 50% of the original activity remained in the leaves of the 35S-NR transformants. NR mRNA was much more stable than NR activity. NR mRNA abundance increased in the leaves of the 35S-NR plants and remained constant in controls for the first 3 d of drought. On the 4th d, however, NR mRNA suddenly decreased in both lines. Rehydration at d 3 caused rapid recovery (within 24 h) of 35S-NR transcripts, but no recovery was observed in the controls. The phosphorylation state of the protein was unchanged by long-term drought. There was a strong correlation between maximal extractable NR activity and ambient photosynthesis in both lines. We conclude that drought first causes increased NR protein turnover and then accelerates NR mRNA turnover. Constitutive NR expression temporarily delayed drought-induced losses in NR activity. 35S-NR expression may therefore allow more rapid recovery of N assimilation following short-term water deficit.
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PMID:Overexpression of nitrate reductase in tobacco delays drought-induced decreases in nitrate reductase activity and mRNA 957 99


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