Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.4 (nitrite reductase)
1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of chlorate-resistant mutants of Azotobacter vinelandii affected in a general control of nitrogen metabolism were isolated. These mutants could not utilize dinitrogen, nitrate, or nitrite as a nitrogen source. The reason for this inability is that they were simultaneously deficient in nitrogenase and nitrate and nitrite reductase activities. They were complemented by a cosmid carrying a DNA fragment of A. vinelandii able to complement ntrA mutants of Escherichia coli, so they seemed to be ntrA-like mutants.
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PMID:Isolation of ntrA-like mutants of Azotobacter vinelandii. 300 6

Operon fusion strains of Escherichia coli K-12 have been used to demonstrate that transcription of the structural gene for NADH-dependent nitrite reductase is regulated by oxygen repression and induction by its substrate, nitrite. This two-stage regulation of nirB is totally dependent upon a functional Fnr protein. Unlike the Fnr-dependent fumarate reductase operon, nirB transcription is not repressed by nitrate. These results suggest that the Fnr protein is simply a positive control protein essential for the derepression of some, but not all, anaerobically-induced operons rather than a more general redox-sensitive regulator, as suggested by the redox control hypothesis for the regulation of gene expression in facultatively anaerobic bacteria.
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PMID:Lack of redox control of the anaerobically-induced nirB+ gene of Escherichia coli K-12. 303 36

Biochemical, microbiological and genetic studies were done to characterize the mechanism of bacterial formation of N-nitrosomorpholine (NMOR) from morpholine and nitrite at neutral pH. In Escherichia coli and Proteus morganii, the nitrosating activity was markedly induced when bacteria were cultured under anaerobiosis in minimal medium containing nitrate, while in the presence of nitrite there was no induction. However, induction of the nitrosating activity in Pseudomonas aeruginosa occurred in anaerobic cultures in the presence of either nitrate or nitrite. The nitrosation capacity was also examined in various E. coli K12 mutants whose structural gene of either nitrate reductase or nitrite reductase was deleted. Nitrosation was not linked to the three (NADH-, formate- and glucose-dependent) nitrite reductases but was directly dependent on the presence of a nitrate reductase.
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PMID:Nitrosamine formation by denitrifying and non-denitrifying bacteria: implication of nitrite reductase and nitrate reductase in nitrosation catalysis. 314 63

The main nitrogen source for most higher plants is soil nitrate. Prior to its incorporation into amino acids, plants reduce nitrate to ammonia in two enzymatic steps. Nitrate is reduced by nitrate reductase to nitrite, which is further reduced to ammonia by nitrite reductase. In this paper, the complete primary sequence of the precursor protein for spinach nitrite reductase has been deduced from cloned cDNAs. The cDNA clones were isolated from a nitrate-induced cDNA library in two ways: through the use of oligonucleotide probes based on partial amino acid sequences of nitrite reductase and through the use of antibodies raised against purified nitrite reductase. The precursor protein for nitrite reductase is 594 amino acids long and has a 32 amino acid extension at the N-terminal end of the mature protein. These 32 amino acids most likely serve as a transit peptide involved in directing this nuclear-encoded protein into the chloroplast. The cDNA hybridizes to a 2.3 kb RNA whose steady-state level is markedly increased upon induction with nitrate.
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PMID:Isolation of cDNA clones coding for spinach nitrite reductase: complete sequence and nitrate induction. 316 66

A new methylammonium-resistant mutant strain from Chlamydomonas reinhardtii, henceforth termed 2172 (ma-2), has been isolated. This mutant is affected in a single mendelian gene different from and linked to the ma-1 locus which is defective in the methylammonium-resistant mutant 2170. Both mutations in ma-1 (2170) and ma-2 (2172) are linked to the nit-1 gene coding for the nitrate reductase apoenzyme. Mutant 2172 is affected in methylammonium but not in ammonium uptake capacity and shows derepressed nitrate and nitrite reductase activities in media containing nitrate plus methylammonium but not in nitrate plus ammonium media. The following two enzymatic components for the transport of both ammonium and methylammonium in wild-type cells have been identified: component 1, with high Vmax and K values, which is constitutive, and component 2, with low Vmax and K values, which is ammonium-repressible. Mutant 2170 lacks component 1 whereas mutant 2172 lacks component 2 for both methylammonium and ammonium transport. From genetic and kinetic evidences we conclude that in C. reinhardtii two different carriers are responsible for the transport of both ammonium and methylammonium and that methylammonium (ammonium) transport is a reversible process probably inhibited by the intracellular ammonium which, in turn, regulates nitrate and nitrite reductase levels.
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PMID:Two different carriers transport both ammonium and methylammonium in Chlamydomonas reinhardtii. 317 May 37

Oxygen caused a reversible inhibition (switch-off) of nitrogenase activity in whole cells of four strains of diazotrophs, the facultative anaerobe Klebsiella pneumoniae and three strains of photosynthetic bacteria (Rhodopseudomonas sphaeroides f. sp. denitrificans and Rhodopseudomonas capsulata strains AD2 and BK5). In K. pneumoniae 50% inhibition of acetylene reduction was attained at an O2 concentration of 0.37 microM. Cyanide (90 microM), which did not affect acetylene reduction but inhibited whole-cell respiration by 60 to 70%, shifted the O2 concentration that caused 50% inhibition of nitrogenase activity to 2.9 microM. A mutant strain of K. pneumoniae, strain AH11, has a respiration rate that is 65 to 75% higher than that of the wild type, but its nitrogenase activity is similar to wild-type activity. Acetylene reduction by whole cells of this mutant was inhibited 50% by 0.20 microM O2. Inhibition by CN- of 40 to 50% of the O2 uptake in the mutant shifted the O2 concentration that caused 50% inhibition of nitrogenase to 1.58 microM. Thus, when the respiration rates were lower, higher oxygen concentrations were required to inhibit nitrogenase. Reversible inhibition of nitrogenase activity in vivo was caused under anaerobic conditions by other electron acceptors. Addition of 2 mM sulfite to cell suspensions of R. capsulata B10 and R. sphaeroides inhibited nitrogenase activity. Nitrite also inhibited acetylene reduction in whole cells of the photodenitrifier R. sphaeroides but not in R. capsulata B10, which is not capable of enzymatic reduction of NO2-. Lower concentrations of NO2- were required to inhibit the activity in NO3- -grown cells, which have higher activities of nitrite reductase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism of nitrogenase switch-off by oxygen. 354 74

Pseudomonas aureofaciens truncates the respiratory reduction of nitrate (denitrification) at the level of N2O. The nitrite reductase from this organism was purified to apparent electrophoretic homogeneity and found to be a blue copper protein. The enzyme contained 2 atoms of copper/85 kDa, both detectable by electron paramagnetic resonance (EPR) spectroscopy. The protein was dimeric, with subunits of identical size (40 +/- 3 kDa). Its pI was 6.05. The EPR spectrum showed an axial signal g at 2.21(8) and g at 2.04(5). The magnitude of the hyperfine splitting (A parallel = 6.36 mT) indicated the presence of type 1 copper only. The electronic spectrum had maxima at 280 nm, 474 nm and 595 nm (epsilon = 7.0 mM-1 cm-1), and a broad shoulder around 780 nm. A copper protein of low molecular mass (15 kDa), with properties similar to azurin, was also isolated from P. aureofaciens. The electronic spectrum of this protein showed a maximum at 624 nm in the visible range (epsilon = 2.5 mM-1 cm-1) and pronounced structures in the ultraviolet region. The EPR parameters were g parallel = 2.26(6) and g perpendicular = 2.05(6), with A parallel = 5.8 mT. The reduced azurin transferred electrons efficiently to nitrite reductase; the product of nitrite reduction was nitric oxide. The specific nitrite-reducing activity with ascorbate-reduced phenazine methosulfate as electron donor was 1 mumol substrate min-1 mg protein-1. The reaction product again was nitric oxide. Nitrous oxide was the reaction product from hydroxylamine and nitrite and from dithionite-reduced methyl viologen and nitrite. No 'oxidase' activity could be demonstrated for the enzyme. Our data disprove the presumed exclusiveness of cytochrome cd1 as nitrite reductase within the genus Pseudomonas.
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PMID:Type 1, blue copper proteins constitute a respiratory nitrite-reducing system in Pseudomonas aureofaciens. 366 26

An electron capture gas-chromatographic technique was developed to continuously measure nitrate (NO3-) reduction during in vitro complementation tests with extracts from Pseudomonas aeruginosa mutants deficient in both assimilatory and dissimilatory nitrate reduction as a result of a single genetic mutation. The procedure involves coupling nitrate reduction to nitrous oxide (N2O) evolution via a series of reactions specific to the denitrification pathway. The assay was dependent on nitrate concentration, and optimal activity was obtained with a final concentration of 0.2% potassium nitrate. The reduction exhibited a stoichiometry of 2:1 (NO3-/N2O), and succinate was the best electron source for the reaction, followed by glucose, pyruvate, and malate. The technique can also be used for continuously monitoring nitrate reduction. The optimal nitrite concentration in the nitrite reductase assay was 0.025%. The initial complementation studies of mutant extracts demonstrated that at least two genes are shared between the two nitrate reduction pathways in P. aeruginosa.
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PMID:Gas chromatographic assay for in vitro complementation of Pseudomonas aeruginosa mutants deficient in nitrate reduction. 391 41

1. The assimilatory nitrite reductase of the N(2)-fixing bacterium Azotobacter chroococcum was prepared in a soluble form from cells grown aerobically with nitrate as the nitrogen source, and some of its properties have been studied. 2. The enzyme is a FAD-dependent metalloprotein (mol.wt. about 67000), which stoicheiometrically catalyses the direct reduction of nitrite to NH(3) with NADH as the electron donor. 3. NADH-nitrite reductase can exist in two either active or inactive interconvertible forms. Inactivation in vitro can be achieved by preincubation with NADH. Nitrite can specifically protect the enzyme against this inactivation and reverse the process once it has occurred. 4. A. chroococcum nitrite reductase is an adaptive enzyme whose formation depends on the presence of either nitrate or nitrite in the nutrient solution. 5. Tungstate inhibits growth of the microorganism very efficiently, by competition with molybdate, when nitrate is the nitrogen source, but does not interfere when nitrite or NH(3) is substituted for nitrate. The addition of tungstate to the culture media results in the loss of nitrate reductase activity but does not affect nitrite reductase.
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PMID:Reduced nicotinamide-adenine dinucleotide-nitrite reductase from Azotobacter chroococcum. 414 87

Kemp, John D. (University of California, Los Angeles), and Daniel E. Atkinson. Nitrite reductase of Escherichia coli specific for reduced nicotinamide adenine dinucleotide. J. Bacteriol. 92:628-634. 1966.-A nitrite reductase specific for reduced nicotinamide adenine dinucleotide (NADH(2)) appears to be responsible for in vivo nitrite reduction by Escherichia coli strain Bn. In extracts, the reduction product is ammonium, and the ratio of NADH(2) oxidized to nitrite reduced or to ammonium produced is 3. The Michaelis constant for nitrite is 10 mum. The enzyme is induced by nitrite, and the ability of intact cells to reduce nitrite parallels the level of NADH(2)-specific nitrite reductase activity demonstrable in cell-free preparations. Crude extracts of strain Bn will also reduce hydroxylamine, but not nitrate or sulfite, at the expense of NADH(2). Kinetic observations indicate that hydroxylamine and nitrite may both be reduced at the same active site. The high apparent Michaelis constant for hydroxylamine (1.5 mm), however, seems to exclude hydroxylamine as an intermediate in nitrite reduction. In vitro activity is enhanced by preincubation with nitrite, and decreased by preincubation with NADH(2).
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PMID:Nitrite reductase of Escherichia coli specific for reduced nicotinamide adenine dinucleotide. 428 93


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