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)

Stoicheometries and rates of proton translocation associated with respiratory reduction of NO3- have been measured for spheroplasts of Escherichia coli grown anaerobically in the presence of NO3-. Observed stoicheiometries [leads to H+/NO3- ratio; P. Mitchell (1966) Chemiosmotic Coupling in Oxidative and Photosynthetic Phosphorylation, Glynn Research, Bodmin] were approx. 4 for L-malate oxidation and approx. 2 for succinate, D-lactate and glycerol oxidation. Measurements of the leads to H+/2e- ratio with formate as the reductant and oxygen or NO3- as the oxidant were complicated by pH changes associated with formate uptake and CO2 formation. Nevertheless, it was possible to conclude that the site of formate oxidation is on the inner aspect of the cytoplasmic membrane, that the leads to H+/O ratio for formate oxidation is approx. 4, and that the leads to H+/NO3- ratio is greater than 2. Measurements of the rate of NO3- penetration into osmotically sensitive spheroplasts demonstrated an electrogenic entry of NO3- anion. The permeability coefficient for nitrate entry at 30 degrees C was between 10(-9) and 10(-10) cm- s(-1). The calculated rate of nitrate entry at the concentration typically used for the assay of nitrate reductase (EC 1.7.99.4) activity was about 0.1% of that required to support the observed rate of nitrate reduction by reduced Benzyl Viologen. Measurements of the distribution of nitrate between the intracellular and extracellular spaces of a haem-less mutant, de-repressed for nitrate reductase but unable to reduce nitrate by the respiratory chain, showed that, irrespective of the presence or the absence of added glucose, nitrate was not concentrated intracellularly. Osmotic-swelling experiments showed that the rate of diffusion of azid anion across the cytoplasmic membrane is relatively low in comparison with the fast diffusion of hydrazoic acid. The inhibitory effect of azide on nitrate reductase was not altered by treatments that modify pH gradients across the cytoplasmic membrane. It is concluded that the nitrate-reducing azide-sensitive site of nitrate reductase is located on the outer aspect of the cytoplasmic membrane. The consequences of this location for mechanisms of proton translocation driven by nitrate reduction are discussed, and lead to the proposal that the nitrate reductase of the cytoplasmic membrane is vectorial, reducing nitrate on the outer aspect of the membrane with 2H+ and 2e- that have crossed from the inner aspect of the membrane.
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PMID:Proton translocation and the respiratory nitrate reductase of Escherichia coli. 0 96

The redox state of cytochrome alpha 3 during in situ respiration of leaves of 20-day-old rice seedlings was assessed by in vivo aerobic assay of nitrate reductase, after 1 min exposure to carbon monoxide. Different stress treatments like water and salt stresses, disintegration of leaf tissues and darkness modified the redox state of cytochrome c oxidase. The dark treatment altered the redox state of cytochrome oxidase from reduced to the oxidized state, as judged by its reaction with CO in CO-sensitive rice cultivar. The water and salt stresses as well as the disintegration of leaf tissue on the contrary altered cytochrome oxidase from the oxidized to its reduced state in CO-insensitive cultivars; probably by changing the cellular integrity, turgidity and structure of mitochondrial membrane, and also due to decreased mitochondrial energization.
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PMID:Modification of the redox state of cytochrome c oxidase of rice due to certain stress treatments. 133 47

Evidence is presented on the effects of low and high concentrations of iron on growth, nutrient uptake (NH+4 and NO3-), photosynthesis (CO2-fixation and O2-evolution) and nitrate reductase (NR) activity of A. doliolum and C. vulgaris under monochromatic irradiation. Control cultures (not treated with FeCl3) showed maximum growth under fluorescent followed by red, yellow, blue and green lights (fluorescent greater than yellow greater than red greater than blue greater than green). The inhibition was of synergistic type under yellow and red lights at all the iron concentrations tested. However, under blue and green lights the interaction was less than additive type. All the processes studied responded in a similar manner to a particular color of light. Under fluorescent light at low Fe concentrations, stimulation of NR, 14CO2-fixation and O2-evolution was noticed in both the test organisms. However, even the lowest concentration of iron tested was inhibitory to these processes under yellow and red lights. Under blue light at 20 micrograms.ml-1 Fe, NR activity was inhibited by 98%. This study clearly demonstrates that metal toxicity to phytoplankton will be greatly affected by spectral quality, hence it will have great significance in limnological research.
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PMID:Impact of spectral quality on toxicity of iron in Anabaena doliolum and Chlorella vulgaris. 158 69

A 3.7-kb DNA region encoding part of the Rhodospirillum rubrum CO oxidation (coo) system was identified by using oligonucleotide probes. Sequence analysis of the cloned region indicated four complete or partial open reading frames (ORFs) with acceptable codon usage. The complete ORFs, the 573-bp cooF and the 1,920-bp cooS, encode an Fe/S protein and the Ni-containing carbon monoxide dehydrogenase (CODH), respectively. The four 4-cysteine motifs encoded by cooF are typical of a class of proteins associated with other oxidoreductases, including formate dehydrogenase, nitrate reductase, dimethyl sulfoxide reductase, and hydrogenase activities. The R. rubrum CODH is 67% similar to the beta subunit of the Clostridium thermoaceticum CODH and 47% similar to the alpha subunit of the Methanothrix soehngenii CODH; an alignment of these three peptides shows relatively limited overall conservation. Kanamycin cassette insertions into cooF and cooS resulted in R. rubrum strains devoid of CO-dependent H2 production with little (cooF::kan) or no (cooS::kan) methyl viologen-linked CODH activity in vitro, but did not dramatically alter their photoheterotrophic growth on malate in the presence of CO. Upstream of cooF is a 567-bp partial ORF, designated cooH, that we ascribe to the CO-induced hydrogenase, based on sequence similarity with other hydrogenases and the elimination of CO-dependent H2 production upon introduction of a cassette into this region. From mutant characterizations, we posit that cooH and cooFS are not cotranscribed. The second partial ORF starts 67 bp downstream of cooS and would be capable of encoding 35 amino acids with an ATP-binding site motif.
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PMID:Genetic and physiological characterization of the Rhodospirillum rubrum carbon monoxide dehydrogenase system. 164 55

Pseudomonas aeruginosa is an obligate respirer which can utilize nitrate as a terminal electron acceptor under anaerobic conditions (denitrification). Immediate, transient regulation of nitrate respiration is mediated by oxygen through the inhibition of nitrate uptake. In order to gain an understanding of the bioenergetics of nitrate transport and its regulation by oxygen, the effects of various metabolic inhibitors on the uptake process and on oxygen regulation were investigated. Nitrate uptake was stimulated by the protonophores carbonyl cyanide m-chlorophenylhydrazone and 2,4-dinitrophenol, indicating that nitrate uptake is not strictly energized by, but may be affected by the proton motive force. Oxygen regulation of nitrate uptake might in part be through redox-sensitive thiol groups since N-ethylmaleimide at high concentrations decreased the rate of nitrate transport. Cells grown with tungstate (deficient in nitrate reductase activity) and azide-treated cells transported nitrate at significantly lower rates than untreated cells, indicating that physiological rates of nitrate transport are dependent on nitrate reduction. Furthermore, tungstate grown cells transported nitrate only in the presence of nitrite, lending support to the nitrate/nitrite antiport model for transport. Oxygen regulation of nitrate transport was relieved (10% that of typical anaerobic rates) by the cytochrome oxygen reductase inhibitors carbon monoxide and cyanide.
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PMID:Nitrate transport and its regulation by O2 in Pseudomonas aeruginosa. 191 Feb 83

Haemophilus ducreyi has traditionally been difficult to identify. We have utilized simple test methods to identify 19 fresh isolates obtained during a recent outbreak of chancroid in Houston and six strains of H. ducreyi from other outbreaks. Tests were performed from growth on chocolate agar after 48 h of incubation at 35 degrees C with increased humidity and CO2. All isolates exhibited typical colonial morphology and Gram stain. Isolates were catalase negative and oxidase and nitrate positive (in enriched broth). The RapID NH system failed to identify these strains because of negative reactions with alkaline phosphatase and nitrate reductase. However, by using the RapID-ANA system, all strains were positive for alkaline phosphatase and arginine, glycine, and serine aminopeptidases. Their biochemical profiles were distinct from those obtained with 66 strains representing 13 species similar to H. ducreyi. We also investigated the use of sodium polyanetholesulfonate (SPS) disk susceptibility to identify and differentiate H. ducreyi from other species. All H. ducreyi isolates were susceptible, as evidenced by the presence of a zone of inhibition with an average size of 15 mm around the SPS disk. With the exceptions of Neisseria gonorrhoeae, Gardnerella vaginalis, and Capnocytophaga spp., no other strain showed any evidence of inhibition. The latter three organisms can be easily differentiated from H. ducreyi by various features including reactions in the RapID-ANA. We conclude that, by considering simple growth and biochemical characteristics, SPS susceptibilities, and reactions in RapID-ANA, it is possible for more clinical laboratories to definitively identify this organism.
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PMID:Use of the RapID-ANA system and sodium polyanetholesulfonate disk susceptibility testing in identifying Haemophilus ducreyi. 215 97

The membrane-bound respiratory particle complex of Pseudomonas aeruginosa, which reduces nitrate to nitrite using formate as the electron donor, was prepared and characterized by e.p.r. and low-temperature magnetic c.d. (m.c.d.) spectroscopy. The particle complex has two enzymic components, namely nitrate reductase (NiR) and formate dehydrogenase (FDH), which are multi-centred proteins containing molybdenum, iron-sulphur clusters and cytochrome. By using results from work on the purified extracted enzymes NiR and FDH to aid in the assignment, it has been possible to observe spectroscopically all the components of the electron-transfer chain in the intact particle. This led to a proposal for the organization of the metal components of the FDH-NiR chain. Molybdenum ions are at opposite ends of the chain and interact with, respectively, the formate-CO2 couple and the nitrate-nitrite couple. The molybdenum ion at the low-potential end of the chain passes electrons to cytochrome b of FDH, a bishistidine-co-ordinated haem with unusual steric restraint at the iron. The next component is a [4Fe-4S] cluster. This comprises all the components of FDH. Electrons are passed to the molybdenum of NiR via a number, probably two, of [4Fe-4S] clusters. No evidence has been found in this work for the presence of a quinone to mediate electron transfer between FDH and NiR. Cytochrome c appears to be able to feed electrons into the chain at the level of one of the [4Fe-4S] centres of NiR.
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PMID:Electron-paramagnetic-resonance and magnetic-circular-dichroism studies on the formate dehydrogenase-nitrate reductase particle from Pseudomonas aeruginosa. 303 83

The comparative study of 44 isolates of Corynebacterium group D2, from urine, most frequently, shows the pathogenic role of these bacteria in urinary tract infection, with or without urinary stones. These microorganisms have an opportunistic behaviour in other non-urinary sites, and become pathogen in immunosuppressed conditions. The rapid tests as urease, glucose acidification, nitrate reductase, associated with multiple resistance to antibiotics (beta-lactams and aminosides) identify easily Corynebacterium group D2, from 48 h cultures under CO2 conditions. The results of MIC determination of 10 antibiotics, show the high activity (100% sensitivity) of vancomycin and pristinamycin, with MIC modes, respectively, 0.5 and 0.03 mg/l. These antibiotics are the most useful for the treatment of non-urinary infections. Among quinolones, the most active agents are ciprofloxacin and ofloxacin (MIC modes: 4 and 2 mg/l), so these antimicrobials could be used for the treatment of urinary tract infections caused by Corynebacterium group D2.
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PMID:[Corynebacterium group D2. Clinical study, biochemical identification and antibiotic sensitivity]. 313 26

Downey, R. J. (University of Notre Dame, Notre Dame, Ind.). Nitrate reductase and respiratory adaptation in Bacillus stearothermophilus. J. Bacteriol. 91:634-641. 1966.-Bacillus stearothermophilus 2184 required nitrate to grow in the absence of oxygen. Like many facultative microorganisms, the growth obtained anaerobically was considerably less than that obtained aerobically, even though the dissimilatory reduction of nitrate is, in effect, anaerobic respiration. The ability to reduce nitrate depended on the induction of nitrate reductase. Although oxygen at low levels did not retard induction of the enzyme, enzyme synthesis was considerably lessened by aeration. A semisynthetic medium containing nitrate supported aerobic growth of the thermophile but did not support anaerobic growth. The adaptation to nitrate resulted in a decrease in the level of cytochrome oxidase normally present in aerobically grown cells. Although the aerobic oxidation of succinate by the respiratory enzymes from aerobically grown cells was inhibited by 2-N-heptyl-4-hydroxyquinoline-N-oxide, the anaerobic oxidation of succinate by nitrate in a similar preparation from nitrate-adapted cells was not. The nitrate reductase in the bacillus was strongly inhibited by cyanide and azide but not by carbon monoxide. The nitrate reductase catalyzed the anaerobic oxidation of reduced nicotinamide adenine dinucleotide, and appeared to transfer electrons from cytochrome b(1) to nitrate. Cytochrome c(1) did not appear to be involved in the transfer.
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PMID:Nitrate reductase and respiratory adaptation in Bacillus stearothermophilus. 428 85

The carbon monoxide oxidases (COXs) purified from the carboxydotrophic bacteria Pseudomonas carboxydohydrogena and Pseudomonas carboxydoflava were found to be molybdenum hydroxylases, identical in cofactor composition and spectral properties to the recently characterized enzyme from Pseudomonas carboxydovorans (O. Meyer, J. Biol. Chem. 257:1333-1341, 1982). All three enzymes exhibited a cofactor composition of two flavin adenine dinucleotides, two molybdenums, eight irons and eight labile sulfides per dimeric molecule, typical for molybdenum-containing iron-sulfur flavoproteins. The millimolar extinction coefficient of the COXs at 450 nm was 72 (per two flavin adenine dinucleotides), a value similar to that of milk xanthine oxidase and chicken liver xanthine dehydrogenase at 450 nm. That molybdopterin, the novel prosthetic group of the molybdenum cofactor of a variety of molybdoenzymes (J. Johnson and K. V. Rajagopalan, Proc. Natl. Acad. Sci. U.S.A. 79:6856-6860, 1982) is also a constituent of COXs from carboxydotrophic bacteria is indicated by the formation of identical fluorescent cofactor derivatives, by complementation of the nitrate reductase activity in extracts of Neurospora crassa nit-l, and by the presence of organic phosphate additional to flavin adenine dinucleotides. Molybdopterin is tightly but noncovalently bound to the protein. COX, sulfite oxidase, xanthine oxidase, and xanthine dehydrogenase each contains 2 mol of molybdopterin per mol of enzyme. The presence of a trichloroacetic acid-releasable, so-far-unidentified, phosphorous-containing moiety in COX is suggested by the results of phosphate analysis.
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PMID:Molybdopterin in carbon monoxide oxidase from carboxydotrophic bacteria. 658 59


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