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

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

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

A useful method for isolating and recognizing Haemophilus ducreyi from chancres and buboes of male patients is presented. A total of 41 clinical isolates of H. ducreyi were recovered from 33 patients over an 8-year period, and the experience with the 15 most recent isolates is presented in detail. Chocolate agar supplemented with 1% Iso VitaleX and 5% sheep blood agar were prepared, using Trypticase soy and Mueller-Hinton Agar bases, and incubation conditions included ambient, capneic, and anaerobic environments. Mueller-Hinton agar was clearly superior over Trypticase soy agar for isolation of H. ducreyi, although there was little difference between 5% sheep blood and supplemented chocolate agar. Growth in ambient air and under anaerobiasis was poor or lacking, whereas growth in 5 to 7% CO2 was good to luxuriant. Heat-inactivated and fresh (unheated)human blood clot tubes also were used for selective isolation. Although the rates of isolation from the two types of clot tube were not significantly different, unheated clot tubes were superior to heated clot tubes because of reduced level of contaminants. Gram stain characteristics taken from blood clot tubes and solid media, cellular and colonial morphology of the bacilli, and lack of oxidase, catalase, and biochemical activity except nitrate reductase were determinant factors. The results of this study demonstrated that successful isolation of H. ducreyi can be achieved with a minimal amount of resources and expertise.
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PMID:Isolation and cultivation of Haemophilus ducreyi. 680 70

This work investigated the usefulness of chlorate resistance as a method for the selection of nitrate reductase negative (NR-) strains from Rhizobium japonicum (61A76) and evaluated the symbiotic, characteristics of these strains. Chlorate resistent strains were selected from populations seeded on CS 7 agar containing 10 or 20 mM KC10, and incubated in 2% air- 98% N2-CO2 (95:5). Over 200 resistant strains were isolated, 58% of which lacked the dissimilatory nitrate reductase. In 12 selected isolates, some strains had also lost the assimilatory nitrate reductase, but all retained hydrogenase activity. Chlorate resistant strains inoculated to soybean seedlings were equal to or better than the parent strain in terms of nodule mass and acetylene reduction. Those strains lacking both assimilatory and dissimilatory nitrate reductase showed the best symbiotic characteristics, suggesting that chlorate resistance in R. japonicum could be a useful method for the selection of strains with superiod nitrogen-fixing characteristics.
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PMID:Free-living and symbiotic characteristics of chlorate resistant mutants of Rhizobium. 719 Aug 66

Tests were conducted to determine the effects of Profenfos [(0-(4-bromo-2-chlorophenyl) 0-ethyl S-n-propyl-phosphorothioat] on fungal populations and some activities in soil. Profenfos (at 5.4 micrograms active ingredient/g dry soil), has a significant adverse effect on the count of total fungi after 2, 4 and 6 weeks after treatment. This effect was completely alleviated after longer incubation. Incorporation of this insecticide into the agar medium inhibited the total count of soil fungi at 6.4 and 38.4 micrograms ml-1. Initial activation followed by a decrease in CO2 output occurred in soil treated with 5.4 micrograms a.i./g. The two doses of Profenfos accelerated urease activity for 6 weeks after soil treatment, but inhibited the enzyme activity after longer periods. An inhibitory effect on nitrate reductase activity was observed with some insecticide treatments in the early stages of incubation followed by an activation in certain cases.
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PMID:Effect of soil treatment with the organophosphorus insecticide Profenfos on the fungal flora and some microbial activities. 792 96

Nitrate reductase (NR), the first enzyme in the nitrate assimilation pathway, is regulated post-transcriptionally in response to light and CO2. In spinach, it has been shown that phosphorylation is one mechanism that mediates this regulation. In this paper, the phosphorylation of NR in Arabidopsis is described in both wild-type and NR- mutant plants. A 110-kDa protein radiolabeled in vivo with 32PO4 was immunoprecipitated with anti-NR antibody from extracts of wild-type plants but not of mutant plants in which the NR gene NIA2 had been deleted. Phosphoamino acid and phosphopeptide analysis showed that, as for spinach, NR from Arabidopsis is phosphorylated on serine and produces multiple phosphopeptides upon digestion with CNBr or trypsin. Analysis of three mutants with lesions in the NIA2 NR structural gene showed that one mutant, chl3-1, has a reduced phosphorylation phenotype that is not complemented by a NR deletion mutant. Comparison of the sequences of the wild-type and chl3-1 NIA2 genes revealed a single base mutation changing a glycine codon to an aspartic acid codon. This glycine, at position 308 in the MoCo domain of NR, is completely conserved in all known eukaryotic NR sequences. Thus, glycine 308 is required for normal activity and phosphorylation of NR, and substitution of this residue with aspartic acid disrupts both processes, most likely by altering the conformation of the NR MoCo domain.
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PMID:A glycine to aspartic acid change in the MoCo domain of nitrate reductase reduces both activity and phosphorylation levels in Arabidopsis. 818 55

Nitrate reductase (NR) is rapidly inactivated by phosphorylation of serine residues in response to loss of light or reduction in CO2 levels. To identify sites within NR protein that play a role in this post-translational regulation, a heterologous expression system and an in vitro inactivation assay for Arabidopsis NR were developed. Protein extracts containing NR kinases and inhibitor proteins were prepared from an NR-defective mutant that had lesions in both the NIA1 and NIA2 NR genes of Arabidopsis. Active NR protein was produced in a Pichia pastoris expression system. Incubation of these two preparations resulted in a Mg-ATP-dependent inactivation of NR that was reversed with EDTA. Mutant forms of NR were constructed, produced in P. pastoris, and tested in the in vitro inactivation assay. Six conserved serine residues in the hinge 1 region of NR, which separates the molybdenum cofactor and heme domains, were specifically targeted for mutagenesis because they are located in a potential regulatory region identified as a target for NR kinases in spinach. A change in Ser-534 to aspartate was found to block NR inactivation; changes in the other five serines had no effect. The aspartate that replaced Ser-534 did not appear to mimic a phosphorylated serine but simply prevented the NR from being inactivated. These results identify Ser-534, located in the hinge 1 of NR and conserved among higher plants NRs, as an essential site for post-translational regulation in vitro.
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PMID:Identification in vitro of a post-translational regulatory site in the hinge 1 region of Arabidopsis nitrate reductase. 872 53


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