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

---

Query: EC:1.7.1.4 (nitrite reductase)
1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synthesis of glutamine synthetase (GS) in anaerobic batch cultures of Escherichia coli was repressed when excess NH4+ was available, but derepressed during growth with a poor nitrogen source. In wild-type bacteria there was only a weak inverse correlation between the activities of GS and glutamate dehydrogenase (GDH) during growth in various media. No positive correlations were found between the activities of GS and nitrite reductase, or between GS and cytochrome c552: both of these proteins were synthesized normally by mutants that contained no active GS. Although activities of GS and GDH were low in two mutants that are unable to synthesize cytochrome c552 or reduce nitrite because of defects in the nirA gene, the nirA defect was separated from the GS and GDH defects by transduction with bacteriophage P1. Attempts to show that catabolite repression of proline oxidase synthesis could be relieved during NH4+ starvation also failed. It is, therefore, unlikely that nitrite reduction or proline oxidation by E. coli are under positive control by GS protein. The regulation of the synthesis of enzymes for the utilization of secondary nitrogen sources in E. coli, therefore, different from that in Klebsiella aerogenes, but is similar to that in Salmonella typhimurium.
...
PMID:Lack of a regulatory function for glutamine synthetase protein in the synthesis of glutamate dehydrogenase and nitrite reductase in Escherichia coli K12. 1 79

Labelling with ferritin-conjugated antibody shows that Pseudomonas cytochrome cd1 is associated with the inner surface of the cytoplasmic membrane. Cytochrome cd1 is however, enriched to the soluble fraction obtained after destruction of Pseudomonas spheroplasts. Comparison of the respiratory nitrite reductase activities, due to this cytochrome, between different cellular fractions and the purified enzyme shows that while the kinetic pattern and the temperature dependence of the activity remain almost the same the molecular activity is enhanced when the enzyme is released from cells. A new assay of respiratory nitrite reductase was developed in this study. The method is based on determination of the stoichiometrical proton consumption accompanying nitrite reduction.
...
PMID:Interaction of Pseudomonas cytochrome cd1 with the cytoplasmic membrane. 10 45

The ratio between the nitrite reductase and cytochrome oxidase activities of Pseudomonas aeruginosa nitrite reductase [EC 1.9.3.2.] varies with kind of C-type cytochrome used as the electron donor. Withe cytochrome c-548, 554 (Micrococcus sp.), the nitrite reductase activity is greater than the cytochrome oxidase activity, while the former is smaller than the latter with cytochrome c-554 (Navicula pelliculosa). The aerobic oxidation catalyzed by this enzyme of denitrifying bacterial ferrocytochrome c is greatly accelerated on addition of nitrite, while that of the algal ferrocytochrome c is not affected or is even depressed by the salt. An accelerative effect of nitrite is generally observed with many kinds of C-type cytochromes which react with the enzyme very or fairly rapidly. The difference in the ratio of the two activities of the enzyme seems to arise according to whether or not nitrite affects the interaction of C-type cytochrome with the enzyme.
...
PMID:Change in the ratio of cytochrome oxidase activity to nitrite reductase activity of Pseudomonas aeruginosa nitrite reductase with the kind of C-type cytochrome used as an electron donor. 17 46

The production of the soluble cytochrome oxidase/nitrite reductase in the bacterium Pseudomonas aeruginosa is favoured by anaerobic conditions and the presence of KNO3(20g/l) in the culture medium. Of three methods commonly used for the disruption of bacterial suspensions (ultrasonication, liquid-shear homogenization and glass-bead grinding), sonication proved the most efficient in releasing the Pseudomonas cytochrome oxidase. A polarographic assay of Pseudomonas cytochrome oxidase activity with sodium ascorbate as substrate and NNN'N'-tetramethyl-p-phenylenediamine dihydrochloride as electron mediator is described. A purification procedure was developed which can be used on the small scale (40-litre cultures) or the large scale (400-litre cultures) and provides high yields of three respiratory-chain proteins, Pseudomonas cytochrome oxidase, cytochrome c551 and azurin, in a pure state. A typical preparation of 250g of Ps.aeruginosa cell paste yielded 180mg of Pseudomonas cytochrome oxidase, 81 mg of Pseudomonas cytochrome c551 and 275mg of Pseudomonas azurin.
...
PMID:A purification procedure for the soluble cytochrome oxidase and some other respiratory proteins from Pseudomonas aeruginosa. 18 50

A c-type cytochrome, cytochrome c-552, from a soluble fraction of an extreme thermophile, Thermus thermophilus HB8, was highly purified and its properties investigated. The absorption peaks were at 552, 522, and 417 nm in the reduced form, and at 408 nm in the oxidized form. The isoelectric point was at PH 10.8, the midpoint redox potential was about +0.23 V, and the molecular weight was about 15,000. The cytochrome c-552 was highly thermoresistant. The cytochrome reacted rapidly with pseudomonas aeruginosa nitrite reductase [EC 1.9.3.2], but slowly with bovine cytochrome oxidase [EC 1.9.3.1], yeast cytochrome c peroxidase [EC 1.11.1.5], or Nitrosomonas europaea hydroxylamine-cytochrome c reductase [EC 1.7.3.4].
...
PMID:Purification and some properties of cytochrome c-552 from an extreme thermophile, Thermus thermophilus HB8. 19 83

Cytochrome c552, which has been implicated as an electron carrier for nitrite reduction by Escherichia coli, has been separated from NADH-nitrite oxidoreductase activity. The cytochrome is therefore not required for the reduction of nitrite by NADH in vitro. Nevertheless, some mutants which were selected by their inability to use nitrite as a nitrogen source during anaerobic growth synthesize neither NADH-nitrite oxidoreductase nor cytochrome c552. The defects in these mutants are due to mutations in a single gene, nirA, which is located at about minute 29 on the recalibrated linkage map. Experiments with an F' plasmid which carries a nirA+ allele established that nirA+ is dominant to the defective allele. Other mutants, defective in nitrate reductase activity because of mutations in the chlA or chlB genes, synthesized nitrite reductase and cytochrome c552 in the absence of nitrate or nitrite. A mutant with a defective fnr gene was also NirA- and, conversely, nirA mutants were Fnr-. In a series of transduction experiments, attempts to separate the nirA and fnr defects were unsuccessful. Furthermore, no complementation was observed when an F' plasmid carrying a defective nirA allele was transferred into the fnr strain. It is concluded that the fnr gene described by Lambden & Guest (1976) is identical to the nirA gene and that its product affects the synthesis or assembly of a variety of anaerobic redox enzymes which include nitrite reductase, cytochrome c552, nitrate reductase, fumarate reductase and formate hydrogenlyase.
...
PMID:The chromosomal location and pleiotropic effects of mutations of the nirA+ gene of Escherichia coli K12: the essential role of nirA+ in nitrite reduction and in other anaerobic redox reactions. 20 51

The reaction of bovine heart ferrocytochrome c with nitrite was studied under various conditions. The reaction product was ferricytochrome c at around pH 5, whereas at around pH 3 it was Compound I, characterized by twin peaks at 529 and 563 nm of equal intensity. However, ferrocytochrome c decreased obeying first-order kinetics over the pH range examined, irrespective of the presence or absence of molecular oxygen. The apparent first-order rate constant was proportional to the square of the nitrite concentration at pH 4.4 and it increased as the pH was lowered. At pH 3 the reaction was so rapid that it had to be followed by stopped-flow and rapid-scanning techniques. The apparent rate constant at this pH was found to increase linearly with the nitrite concentration. Based on these results the active species of nitrite was concluded to be dinitrogen trioxide at pH 4.4 and nitrosonium ion, no+, at pH 3. Compound II was formed by reaction of ferrocytochrome c and NO gas at acidic and alkaline pH values. The absorption peaks were at 533 and 563 nm at pH 3, and at 538 and 567 nm at pH 12.9. This compound was also formed by reducing Compound I with reductants. Compound I prepared from ferricytochrome c and NO was stable below pH 6. However, appreciable absorption peaks for ferrocytochrome c appeared between pH 8 and 10, because Compound I was dissociated into ferrocytochrome c and NO+, and because ferrocytochrome c thus formed reacted with NO very slowly in this pH region. Saccharomyces ferricytochrome c under NO gas behaved differently from mammalian cytochrome, indicating the significance of the nature of the heme environment in determing the reactivity. Only at extreme pH values was Compound II formed exclusively and persisted. A model system for dissimilatory nitrite reductase was constructed by using bovine heart cytochrome c, nitrite and NADH plus PMS at pH 3.3, and a scheme involving cyclic turnover of ferrocytochrome c, Compound I and Compound II is presented, with kinetic parameters.
...
PMID:Reaction of cytochrome c with nitrite and nitric oxide. A model of dissimilatory nitrite reductase. 21 67

NADH-nitrite oxidoreductase (EC 1.6.4) was purified to better than 95% homogeneity from batch cultures of Escherichia coli strain OR75Ch15, which is partially constitutive for nitrite reductase synthesis. Yields of purified enzyme were low, mainly because of a large loss of activity during chromatography on DEAE-cellulose. The quantitative separation of cytochrome c-552 from nitrite reductase activity resulted in an increase in the specific activity of the enzyme: this cytochrome is not therefore an integral part of nitrite reductase. The subunit molecular weights of nitrite reductase and of a haemoprotein contaminant, as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, were 88000 and 80000 respectively. The sedimentation coefficient was calculated to be in the range 8.5-9.5S, consistent with a mol.wt. of 190000. It is suggested therefore that the native enzyme is a dimer with two identical or similar-sized subunits. Purest samples contained 0.4 mol of flavin/mol of enzyme, but no detectable haem. Catalytic activity was totally inhibited by 20 micron-p-chloromercuribenzoate and 1 mM-cyanide, slightly inhibited by 1 micron-sulphite and 10mM-arsenite, but insensitive to 1 mM-2,2'-bipyridine, 4mM-1,10-phenanthroline and 10mM-NaN3. Three molecules of NADH were oxidized for each NO2-ion reduced: the product of the reaction is therefore assumed to be NH4+. The specific activity of hydroxylamine reductase increased at each step in the purification of nitrite reductase, and the elution profiles for these two activities during chromatography on DEAE-Sephadex were coincident. It is likely that a single enzyme is responsible for both activities.
...
PMID:Purification and properties of nitrite reductase from Escherichia coli K12. 21 42

The integrated rate law for the reaction of the nitrite reductase of Paracoccus denitrificans, a cytochrome cd, has been established for turnover assays using donor ferrocytochromes c and either nitrite or molecular oxygen as the ultimate acceptor. The time course for the concentration of ferrocytochrome follows the law: formula: (see text), where S is the concentration of donor ferrocytochrome c, So is the initial concentration, t is time, and u1, u2, and u3 are empirical parameters that are constant for a given experiment but depend upon the initial substrate concentration. In particular, all the u1 increase with decreasing initial ferrocytochrome concentration. Saturation of reaction rates at high donor ferrocytochrome concentrations was not observed. The parameter u1 was proportional to the enzyme concentration while u2 and u3 were not. The form of the integrated rate law and the behavior of the u1 impose severe restrictions on possible kinetic schemes for the activity of the enzyme. Contemporary mechanisms that have been proposed for mitochondrial oxidase aa3 are examined and found to be inadequate to explain the reactivity of cytochrome cd. The simplest interpretations of the cytochrome cd data suggest that the enzyme does not bind the ferri and ferro forms of donor cytochromes c with equal affinity and that the enzyme is subject to inhibition by a product of reaction. Eucaryotic horse cytochrome c reacts with the Paracoccus cytochrome cd with 77% of the activity when Paracoccus cytochrome c550 is used as the electron donor.
...
PMID:Implications of the integrated rate law for the reactions of Paracoccus denitrificans nitrite reductase. 22 18

The ability of the oxidized and singly reduced species of several bipyridylium cations to cross the cytoplasmic membrane of Escherichia coli was studied to locate the sites of reaction of the dyes with anaerobic respiratory enzymes. Benzyl Viologen radical crossed the membrane rapidly, whereas the oxidized species did not. The oxidized or radical species of Methyl Viologen, Morfamquat or Diquat did not rapidly cross the membrane. It was also shown that the dithionite anion does not cross the cytoplasmic membrane of E. coli. Diquat radical donates electrons to the nitrate reductase pathway at the periplasmic aspect of the membrane, whereas Benzyl Viologen radical reacted directly with nitrate reductase itself (EC 1.7.99.4) at the cytoplasmic aspect of the membrane. Thus the pathway of electron transfer in the nitrate reductase pathway is transmembranous. Formate hydrogenlyase (EC 1.2.1.2) and an uncharacterized nitrite reductase activity react with bipyridylium dyes at the periplasmic aspect of the membrane. Fumarate reductase (succinate dehydrogenase; EC 1.3.99.1) reacts with bipyridylium radicals, and formate dehydrogenase (cytochrome) (EC 1.2.2.1) with ferricyanide, at the cytoplasmic aspect of the membrane. The differing charge and membrane permeation of oxidized and radical species of bipyridylium dyes greatly complicate their use as potentiometric mediators in suspensions of cells or membrane vesicles.
...
PMID:Sites and specificity of the reaction of bipyridylium compounds with anaerobic respiratory enzymes of Escherichia coli. Effects of permeability barriers imposed by the cytoplasmic membrane. 32 10


1 2 3 4 5 6 7 8 9 10 Next >>

---