Nitrate Reductases
Mostrando 25-36 de 73 artigos, teses e dissertações.
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25. The nasFEDCBA operon for nitrate and nitrite assimilation in Klebsiella pneumoniae M5al.
Klebsiella pneumoniae can use nitrate and nitrite as sole nitrogen sources through the nitrate assimilation pathway. We previously identified structural genes for assimilatory nitrate and nitrite reductases, nasA and nasB, respectively. We report here our further identification of four genes, nasFEDC, upstream of the nasBA genes. The nasFEDCBA genes probably
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26. Properties of a Thermostable Nitrate Reductase from the Hyperthermophilic Archaeon Pyrobaculum aerophilum
The nitrate reductase of the hyperthermophilic archaeon Pyrobaculum aerophilum was purified 137-fold from the cytoplasmic membrane. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, the enzyme complex consists of three subunits with apparent molecular weights of 130,000, 52,000, and 32,000. The enzyme contained molybdenum (0.8-mol/
American Society for Microbiology.
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27. Feedback Regulation of Nitrate Influx in Barley Roots by Nitrate, Nitrite, and Ammonium.
The short-lived radiotracer 13N was used to study feedback regulation of nitrate influx through the inducible high-affinity transport system of barley (Hordeum vulgare L. cv Steptoe) roots. Both wild-type plants and the mutant line Az12:Az70 (genotype nar1a;nar7w), which is deficient in the NADH-specific and NAD(P)H-bispecific nitrate reductases (R.L. Warner
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28. Isolation and characterization of the nitrate reductase structural gene of Chlamydomonas reinhardtii.
The nitrate reductase structural gene of Chlamydomonas reinhardtii has been isolated from a genomic library by using a nitrate reductase cDNA probe from barley. Restriction fragment length polymorphism analyses mapped the Chlamydomonas clone (B6a) to the nitrate reductase structural gene locus nit-1. Overlapping inserts cover a region of the genome of about
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29. Genetically engineered mutant of the cyanobacterium Synechococcus PCC 7942 defective in nitrate transport
Nitrate-grown cells of Synechococcus PCC 7942 (Anacystis nidulans R2) contain a 45-kDa protein as a major protein in the cytoplasmic membrane but ammonium-grown cells lack it. A mutant (M45) was constructed by inactivating the gene encoding the 45-kDa protein. M45 did not grow under low concentrations of nitrate but high concentrations of nitrate could suppo
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30. Expression of the Enzymes of Nitrate Reduction during the Anaerobic Germination of Rice.
During the anaerobic germination of rice (Oryza sativa L.), nitrate is translocated from the caryopsis and assimilated into the coleoptile (R. Reggiani, M. Mattana, N. Aurisano, A. Bertani [1993] Plant Cell Physiol 34: 379-383). Using antibodies against nitrate and nitrite reductases, proteins with the expected molecular mass were recognized by western blot
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31. The terminal reductases for selenate and nitrate respiration in Thauera selenatis are two distinct enzymes.
A number of approaches have been used to show that a recently isolated selenate-respiring bacterium, Thauera selenatis, is able to synthesize both a selenate reductase (SR) and a nitrate reductase (NR). (i) The pH optimum of the SR was found to be 6.0; that of the NR was 7.0. (ii) The presence of nitrate did not inhibit selenate reduction in selenate-grown c
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32. Mass Spectrometric Studies of the Effect of pH on the Accumulation of Intermediates in Denitrification by Paracoccus denitrificans
We have used a quadrupole mass spectrometer with a gas-permeable membrane inlet for continuous measurements of the production of N2O and N2 from nitrate or nitrite by cell suspensions of Paracoccus denitrificans. The use of nitrate and nitrite labeled with 15N was shown to simplify the interpretation of the results when these gases were measured. This approa
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33. Evidence for a Second Nitrate Reductase Activity That Is Distinct from the Respiratory Enzyme in Salmonella typhimurium
Significant nitrate reductase activity was detected in mutants of Salmonella typhimurium which mapped at or near chlC and which were incapable of growth with nitrate as electron acceptor. The same mutants were sensitive to chlorate and performed sufficient nitrate reduction to permit anaerobic growth with nitrate as the sole nitrogen source in media containi
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34. Induction and Repression of Nitrate Reductase in Neurospora crassa
Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several Neurospora mutations on the regulation of this enzyme are shown: (i) the mutants, nit-1 and nit-3, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NAD
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35. Properties of Bromphenol Blue as an Electron Donor for Higher Plant NADH: Nitrate Reductase 1
Bromphenol blue, which was reduced with dithionite, was found to support nitrate reduction catalyzed by squash NADH:nitrate reductase at a rate about 5 times greater than NADH with freshly prepared enzyme and 10 times or more with enzyme having been frozen and thawed. Kinetic analysis of bromphenol blue as a substrate for squash nitrate reductase yielded app
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36. Nodule and Leaf Nitrate Reductases and Nitrogen Fixation in Medicago sativa L. under Water Stress
The effect of water stress on patterns of nitrate reductase activity in the leaves and nodules and on nitrogen fixation were investigated in Medicago sativa L. plants watered 1 week before drought with or without NO3−. Nitrogen fixation was decreased by water stress and also inhibited strongly by the presence of NO3−. During drought, leaf nitrate reducta