Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.1 (nitrate reductase)
 3,728 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

Maize (Zea mays L.) plants were grown to the nine-leaf stage. Despite a saturating N supply, the youngest mature leaves (seventh position on the stem) contained little NO3- reserve. Droughted plants (deprived of nutrient solution) showed changes in foliar enzyme activities, mRNA accumulation, photosynthesis, and carbohydrate and amino acid contents. Total leaf water potential and CO2 assimilation rates, measured 3 h into the photoperiod, decreased 3 d after the onset of drought. Starch, glucose, fructose, and amino acids, but not sucrose (Suc), accumulated in the leaves of droughted plants. Maximal extractable phosphoenolpyruvate carboxylase activities increased slightly during water deficit, whereas the sensitivity of this enzyme to the inhibitor malate decreased. Maximal extractable Suc phosphate synthase activities decreased as a result of water stress, and there was an increase in the sensitivity to the inhibitor orthophosphate. A correlation between maximal extractable foliar nitrate reductase (NR) activity and the rate of CO2 assimilation was observed. The NR activation state and maximal extractable NR activity declined rapidly in response to drought. Photosynthesis and NR activity recovered rapidly when nutrient solution was restored at this point. The decrease in maximal extractable NR activity was accompanied by a decrease in NR transcripts, whereas Suc phosphate synthase and phosphoenolpyruvate carboxylase mRNAs were much less affected. The coordination of N and C metabolism is retained during drought conditions via modulation of the activities of Suc phosphate synthase and NR commensurate with the prevailing rate of photosynthesis.
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PMID:Drought-induced effects on nitrate reductase activity and mRNA and on the coordination of nitrogen and carbon metabolism in maize leaves 957 98

Transformed (cauliflower mosaic virus 35S promoter [35S]) tobacco (Nicotiana plumbaginifolia L.) plants constitutively expressing nitrate reductase (NR) and untransformed controls were subjected to drought for 5 d. Drought-induced changes in biomass accumulation and photosynthesis were comparable in both lines of plants. After 4 d of water deprivation, a large increase in the ratio of shoot dry weight to fresh weight was observed, together with a decrease in the rate of photosynthetic CO2 assimilation. Foliar sucrose increased in both lines during water stress, but hexoses increased only in leaves from untransformed controls. Foliar NO3- decreased rapidly in both lines and was halved within 2 d of the onset of water deprivation. Total foliar amino acids decreased in leaves of both lines following water deprivation. After 4 d of water deprivation no NR activity could be detected in leaves of untransformed plants, whereas about 50% of the original activity remained in the leaves of the 35S-NR transformants. NR mRNA was much more stable than NR activity. NR mRNA abundance increased in the leaves of the 35S-NR plants and remained constant in controls for the first 3 d of drought. On the 4th d, however, NR mRNA suddenly decreased in both lines. Rehydration at d 3 caused rapid recovery (within 24 h) of 35S-NR transcripts, but no recovery was observed in the controls. The phosphorylation state of the protein was unchanged by long-term drought. There was a strong correlation between maximal extractable NR activity and ambient photosynthesis in both lines. We conclude that drought first causes increased NR protein turnover and then accelerates NR mRNA turnover. Constitutive NR expression temporarily delayed drought-induced losses in NR activity. 35S-NR expression may therefore allow more rapid recovery of N assimilation following short-term water deficit.
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PMID:Overexpression of nitrate reductase in tobacco delays drought-induced decreases in nitrate reductase activity and mRNA 957 99


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