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)

Seventeen strains of the new species Bacillus azotoformans were isolated by enrichment culture in peptone broth inoculated with pasteurized soil and then incubated under N2O at 32 degrees C. The bacterium is a Gram-negative rod, motile with peritrichous flagella, which produces oval spores without exosporia in swollen sporangia. However, the cells have thick walls, mesosomes, and persistent septa characteristic of Gram-positive bacteria. The bacterium lacks fermentative activity, does not attack carbohydrates, has complex growth requirements, and will grow anaerobically only if one of the following electron acceptors is present: NO3-, NO2-, N2O, S4O6--, or fumarate. Nitrate, nitrite, and nitrous oxide are denitrified with the production of N2. The microorganism is mesophilic, gives a positive oxidase reaction, synthesizes a type c cytochrome, and does not hydrolyse gelatin, starch, or "Tween 80." Poly-beta-hydroxybutyric acid is snythesized when the bacterium is grown in a medium containing DL-3-hydroxybutyrate. The following enzymes are present: nitrate reductase A, respiratory nitrite reductase, tetrathionate and fumarate reductases, and L-glutamate dehydrogenase. The following enzymes are absent: thiosulfate reductase, urease, lecithinase, arginine dihydrolase, phenylalanine deaminase, and catalase. For the 17 strains, the mean value of the G = C percent of the DNA is 39.8 +/- 1.2. All the strains are highly similar.
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PMID:[Morphological, physiological and taxonomic studies of Bacillus azotoformans]. 65 12

The denitrifying capacity of 15 strains of Bacillus licheniformis was evaluated. In general, N2 production by the cultures on complex media containing NO3- is irregular and quite slow and three of the strains never produce gas. Bacillus licheniformis grows rapidly in anaerobiosis on peptone medium containing NO3- which is reduced to NO2-. None of the strains grow in peptone medium with NO2- or N2O as the respiratory substrate, nor do they grow under an atmosphere of 10% NO-90% N2. Denitrification was studied in cell suspensions using gas chromatography. N2O production from NO3- or NO2- is always weak at best; nitric oxide is reduced to N2O at an appreciable rate. All the strains synthesize nitrate reductase A in anaerobiosis when NO3- is present. In cell extracts, nitrite reductase activity is always negligible or nil with tetramethyl-p-phenylenediamine as an electron donor.
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PMID:[Denitrification by Bacillus licheniformis]. 75 76

The strains were isolated from soil by enrichment in a liquid minimal medium containing ethanol, acetate, succinate, L-malate or tartrate, under an N2O atmosphere at 32 degrees C. All fourteen strains can use the following 25 sources of carbon and energy under aerobic conditions: glycerate, ethanol, propanol, acetate, butyrate, malonate, succinate, glutarate, sebacate, glycollate, L-lactate, D-lactate, L-malate, DL-3-hydroxybutyrate, pyruvate, fumarate, itaconate, mesaconate, crotonate, L-alpha-alanine, D-alpha-alanine, L-leucine, asparagine, L-tyrosine, and L-proline. They hydrolyze Tween 80 but not gelatin. Nitrate is used as nitrogen source. Nitrate reductase A and respiratory nitrite reductase are present. Four of the strains are clearly and easily distinguishable from the others on the basis of six characters: special morphology of colonies; in ability to use isovalerate and DL-valine, inability to use glucose, absence of exocellular amylase, and high level of metapyrocatechase. Their G + C content is 66-67%. One of the strains is distinct from the others by the yellow pigmentation of its colonies, its ability to use D-glucuronate, trehalose, D-sorbitol and citraconate, ability to grow at 4 degrees but not at 40 degrees, and a lower G + C content: 63%. One strain accumulates poly-beta-hydroxybutyrate. This work confirms the well-known, wide variability of the bacteria belonging to the P. stutzeri group. Denitrification by two of the strains was quantitatively studied using cell suspensions. Cells from NO-3-containing anaerobic cultures reduce NO-3, NO-2 and NO to N2O and N2; they reduce slowly N2O to N2. Cells grown in anaerobic cultures under N2O also reduce NO-3, NO-2 and NO to N2O and N2 but they reduce N2O rapidly to N2.
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PMID:[Study of 14 denitrifying soil bacteria of the "pseudomonas stutzeri" group isolated by enrichment culture in the presence of nitrous oxide (author's transl)]. 86 7

Denitrification in a thermophile isolated on nitrite containing-medium (5 g/l) was studied by means of Warburg respirometry and gas chromatography. This strain seems to denitrify nitrite more rapidly than nitrate. Extracts of cells grown anaerobically on nitrate have dissimilatory nitrate reductase (type A); extracts of cells grown aerobically without nitrate have raised levels of the two types of nitrate reductase A and B. The optimal temperature for enzyme A activity is 60 degrees C. Nitrite reductase activity was measured using yeast extract as electron donor. For nitric oxide reductase activity, yeast extract is as efficient an electron donor as sodium lactate. Nitrous oxide reductase activity was found only in the 4 000 g supernatant showing the particulate nature of the enzyme. A mixture of FAD, FMN and NADH served as electron donor. Using acetylene as an inhibitor of nitrous oxide reduction in both whole cells and extracts, we showed that this gas is an intermediate compound in the reduction of NO to N2.
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PMID:[Denitrification in a sporulating thermophilic bacterium]. 91 Nov 9

The described bacterium was isolated by enrichment culture in peptone broth inoculated with garden soil, pasteurized and then put to incubate under N2O at 32 degrees. It is a Gram-negative rod, motile with peritrichous flagella, and producing oval spores without exosporium in swollen sporangia. However, cells have the thick walls, mesosomes and persistant septa characteristic of Gram-positive bacteria. It lacks fermentative activity, does not attack carbohydrates, has complex growth requirements, and will grow anaerobically only if one of the following electron acceptors is present: NO3, NO2, N2O, S4O6, and fumarate. Nitrate, nitrite, and nitrous oxide are denitrified with production of N2. The microorganism is mesophilic, gives a positive oxidase reaction, synthesizes a type of c cytochrome, and does not hydrolyse gelatin, starch nor "Tween 80". The following enzymes are present: nitrate reductase A, respiratory nitrite reductase, tetrathionate and fumarate reductases, L-glutamate dehydrogenase, and superoxide dismutase. The following enzymes are absent: thiosulfate reductase, urease, lecithinase, arginine dihydrolase, L-alanine dehydrogenase, phenylalanine desaminase, and catalase. The GC% of its DNA is 39. The bacterium described can be considered to be a new species. We propose the name Bacillus azotoformans n. sp.
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PMID:[A new, sporulating, denitrifying, mesophilic bacterium: Bacillus azotoformans N. SP. (author's transl)]. 102 Aug 72

Under anaerobic circumstances in the presence of nitrate Paracoccus denitrificans is able to denitrify. The properties of the reductases involved in nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase are described. For that purpose not only the properties of the enzymes of P. denitrificans are considered but also those from Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas stutzeri. Nitrate reductase consists of three subunits: the alpha subunit contains the molybdenum cofactor, the beta subunit contains the iron sulfur clusters, and the gamma subunit is a special cytochrome b. Nitrate is reduced at the cytoplasmic side of the membrane and evidence for the presence of a nitrate-nitrite antiporter is presented. Electron flow is from ubiquinol via the specific cytochrome b to the nitrate reductase. Nitrite reductase (which is identical to cytochrome cd1) and nitrous oxide reductase are periplasmic proteins. Nitric oxide reductase is a membrane-bound enzyme. The bc1 complex is involved in electron flow to these reductases and the whole reaction takes place at the periplasmic side of the membrane. It is now firmly established that NO is an obligatory intermediate between nitrite and nitrous oxide. Nitrous oxide reductase is a multi-copper protein. A large number of genes is involved in the acquisition of molybdenum and copper, the formation of the molybdenum cofactor, and the insertion of the metals. It is estimated that at least 40 genes are involved in the process of denitrification. The control of the expression of these genes in P. denitrificans is totally unknown. As an example of such complex regulatory systems the function of the fnr, narX, and narL gene products in the expression of nitrate reductase in E. coli is described. The control of the effects of oxygen on the reduction of nitrate, nitrite, and nitrous oxide are discussed. Oxygen inhibits reduction of nitrate by prevention of nitrate uptake in the cell. In the case of nitrite and nitrous oxide a competition between reductases and oxidases for a limited supply of electrons from primary dehydrogenases seems to play an important role. Under some circumstances NO formed from nitrite may inhibit oxidases, resulting in a redistribution of electron flow from oxygen to nitrite. P. denitrificans contains three main oxidases: cytochrome aa3, cytochrome o, and cytochrome co. Cytochrome o is proton translocating and receives its electrons from ubiquinol. Some properties of cytochrome co, which receives its electrons from cytochrome c, are reported.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Metabolic regulation including anaerobic metabolism in Paracoccus denitrificans. 205 Jun 53

Propionibacterium acnes P13 was isolated from human feces. The bacterium produced a particulate nitrate reductase and a soluble nitrite reductase when grown with nitrate or nitrite. Reduced viologen dyes were the preferred electron donors for both enzymes. Nitrous oxide reductase was never detected. Specific growth rates were increased by nitrate during growth in batch culture. Culture pH strongly influenced the products of dissimilatory nitrate reduction. Nitrate was principally converted to nitrite at alkaline pH, whereas nitrous oxide was the major product of nitrate reduction when the bacteria were grown at pH 6.0. Growth yields were increased by nitrate in electron acceptor-limited chemostats, where nitrate was reduced to nitrite, showing that dissimilatory nitrate reduction was an energetically favorable process in P. acnes. Nitrate had little effect on the amounts of fermentation products formed, but molar ratios of acetate to propionate were higher in the nitrate chemostats. Low concentrations of nitrite (ca. 0.2 mM) inhibited growth of P. acnes in batch culture. The nitrite was slowly reduced to nitrous oxide, enabling growth to occur, suggesting that denitrification functions as a detoxification mechanism.
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PMID:Dissimilatory nitrate reduction by Propionibacterium acnes. 262 64

We have developed a rapid and sensitive fluorimetric method, based on the formation of a fluorescent product from nitrosation of 2,3-diaminonaphthalene, for measuring the ability of bacteria to catalyze nitrosation of amines. We have shown in Escherichia coli that nitrosation can be induced under anaerobic conditions by nitrite and nitrate, that formate is the most efficient electron donor for this reaction, and that nitrosation may be catalyzed by nitrate reductase (EC 1.7.99.4). The narG mutants defective in nitrate reductase do not catalyze nitrosation, and the fnr gene is essential for nitrosation. Induction by nitrite or nitrate of nitrosation, N2O production, and nitrate reductase activity all require the narL gene.
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PMID:Bacterial catalysis of nitrosation: involvement of the nar operon of Escherichia coli. 327 20

Formation of nitrate reductase (NaR) and nitrous oxide reductase (N2OR) by a Pseudomonas sp. G59 did not occur in aerobic or anaerobic conditions, but was observed in a microaerobic incubation in which an anaerobically grown culture was agitated in a sealed vessel initially containing 20 kPa oxygen in the headspace. During the microaerobic incubation, the oxygen concentration in the headspace decreased and dissolved oxygen reached 0.1-0.2 kPa. NaR activity was detected immediately and N2OR activity after 3 h of incubation irrespective of the presence or absence of NO3- or N2O. In the presence of NO3-, NO2- was accumulated as a major product, but N2O was observed in low concentrations only after N2OR appeared. After microaerobic incubation for 3 h, N2OR formation continued even anaerobically in an atmosphere of N2O. In contrast, Escherichia coli formed NaR not only microaerobically but also anaerobically. However, NaR formation by E. coli was inhibited by sodium fluoride under anaerobic, but not under microaerobic conditions. The Pseudomonas culture did not possess fermentative activity. It is suggested that the dependence on microaerobiosis for the formation of these reductases by the Pseudomonas culture was due to an inability to produce energy anaerobically until these anaerobic respiratory enzymes were formed.
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PMID:Temporary low oxygen conditions for the formation of nitrate reductase and nitrous oxide reductase by denitrifying Pseudomonas sp. G59. 374 33

Escherichia coli K12 reduces nitrous oxide stoichiometrically to molecular nitrogen with rates of 1.9 mumol/h x mg protein. The activity is induced by anaerobiosis and nitrate. N2-formation from N2O is inhibited by C2H2 (Ki approximately 0.03 mM in the medium) and nitrite (Ki = 0.3 mM) but not by azide. A mutant defective in FNR synthesis is unable to reduce N2O to N2. The reaction in the wild type could routinely be followed by gas chromatography and alternatively by mass spectrometry measuring the formation of 15N2 from 15N2O. The enzyme catalyzing N2O-reduction in E. coli could not be identified; it is probably neither nitrate reductase nor nitrogenase. E. coli does not grow with N2O as sole respiratory electron acceptor. N2O-reduction might not have a physiological role in E. coli, and the enzyme involved might catalyze something else in nature, as it has a low affinity for the substrate N2O (apparent Km approximately 3.0 mM). The capability for N2O-reduction to N2 is not restricted to E. coli but is also demonstrable in Yersinia kristensenii and Buttiauxella agrestis of the Enterobacteriaceae. E. coli is able to produce NO and N2O from nitrite by nitrate reductase, depending on the assay conditions. In such experiments NO2- is not reduced to N2 because of the high demand for N2O of N2O-reduction and the inhibitory effect of NO2- on this reaction.
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PMID:The reduction of nitrous oxide to dinitrogen by Escherichia coli. 829 9


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