Isotopic Fractionation During Reduction of Nitrate and Nitrite by Extracts of Spinach Leaves

1985 ◽  
Vol 12 (6) ◽  
pp. 631 ◽  
Author(s):  
SF Ledgard ◽  
KC Woo ◽  
FJ Bergersen
Keyword(s):  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Spinacia Oleracea ◽  
Reductase Activity ◽  
Isotopic Fractionation ◽  
Cytosolic Extract ◽  
Nitrite Reductase Activity ◽  
Reconstituted System ◽  
No2 Reduction ◽  
Nitrate And Nitrite

The isotopic fractionations of nitrogen during the reduction of NO3- and NO2- in a cytosolic fraction and in a chloroplast preparation from spinach (Spinacia oleracea L.) leaves were determined. The reduction of NO3- to NH3 was studied using a reconstituted system containing cytosolic extract and intact chloroplasts, while a chloroplast system was used for NO2- reduction. In the reconstituted systems the ratio of nitrate reductase activity to nitrite reductase activity had a large effect on the relative amounts of NO2- and NH3 formed. Ammonia predominated when the nitrate reductase to nitrite reductase activity ratio was 1 : 5 and this ratio was used in the isotopic fractionation studies. Significant isotopic fractionation of N was observed in the reconstituted system but not in the chloroplast system. This indicates that the observed isotopic fractionation was associated with the reduction of NO3- to NO2- by nitrate reductase. The isotopic fractionation (i.e. δ15Nproduct - δ15Nsubstrate) for this reaction was - 15‰.

scholarly journals Nitrogen and Oxygen Regulation of Bacillus subtilis nasDEF Encoding NADH-Dependent Nitrite Reductase by TnrA and ResDE

1998 ◽  
Vol 180 (20) ◽  
pp. 5344-5350 ◽  
Author(s):  
Michiko M. Nakano ◽  
Tamara Hoffmann ◽  
Yi Zhu ◽  
Dieter Jahn
Keyword(s):  
Bacillus Subtilis ◽  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Nitrogen Limitation ◽  
Reductase Activity ◽  
Anaerobic Respiration ◽  
Regulatory System ◽  
Nitrate Respiration ◽  
Nitrite Reductase Activity ◽  
Nitrate And Nitrite

ABSTRACT The nitrate and nitrite reductases of Bacillus subtilishave two different physiological functions. Under conditions of nitrogen limitation, these enzymes catalyze the reduction of nitrate via nitrite to ammonia for the anabolic incorporation of nitrogen into biomolecules. They also function catabolically in anaerobic respiration, which involves the use of nitrate and nitrite as terminal electron acceptors. Two distinct nitrate reductases, encoded bynarGHI and nasBC, function in anabolic and catabolic nitrogen metabolism, respectively. However, as reported herein, a single NADH-dependent, soluble nitrite reductase encoded by the nasDE genes is required for both catabolic and anabolic processes. The nasDE genes, together with nasBC(encoding assimilatory nitrate reductase) and nasF(required for nitrite reductase siroheme cofactor formation), constitute the nas operon. Data presented show that transcription of nasDEF is driven not only by the previously characterized nas operon promoter but also from an internal promoter residing between the nasC andnasD genes. Transcription from both promoters is activated by nitrogen limitation during aerobic growth by the nitrogen regulator, TnrA. However, under conditions of oxygen limitation,nasDEF expression and nitrite reductase activity were significantly induced. Anaerobic induction of nasDEFrequired the ResDE two-component regulatory system and the presence of nitrite, indicating partial coregulation of NasDEF with the respiratory nitrate reductase NarGHI during nitrate respiration.

scholarly journals Effect of tungsten on nitrate and nitrite reductases in Azospirillum brasilense Sp7

1991 ◽  
Vol 37 (10) ◽  
pp. 744-750 ◽  
Author(s):  
Christian Chauret ◽  
Roger Knowles
Keyword(s):  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Azospirillum Brasilense ◽  
Nitrate Reductase Activity ◽  
Paracoccus Denitrificans ◽  
Reductase Activity ◽  
Whole Cells ◽  
Azospirillum Brasilense Sp7 ◽  
Nitrite Reductase Activity ◽  
Nitrate And Nitrite

Tungstate, at concentrations that completely suppressed nitrate reductase activity in Paracoccus denitrificans, caused only partial inhibition of nitrate reductase in Azospirillum brasilense Sp7. Nitrate reductase activity in cell-free extracts was much more sensitive than whole cells to tungstate, suggesting that there may be a barrier to its transport. Nitrite reductase activity was partially inhibited by tungstate in both whole cells and cell-free extracts. Azospirillum brasilense apparently scavenged enough contaminating molybdenum from molybdenum-limited medium to allow maximum nitrate reductase activity, which was not stimulated by added molybdate. Cells grown in molybdenum-depleted medium could not reduce nitrate. Nitrate concentrations less than 0.25 mM inhibited activity, but not synthesis, of nitrite reductase and caused significant accumulation of nitrite during reduction of nitrate. Key words: Azospirillum brasilense, Paracoccus denitrificans, nitrate reductase, nitrite reductase, tungsten, molybdenum, denitrification.

Effects of oxygen on each step of denitrification on Pseudomonas nautica

1989 ◽  
Vol 35 (11) ◽  
pp. 1061-1064 ◽  
Author(s):  
P. Bonin ◽  
M. Gilewicz ◽  
J. C. Bertrand
Keyword(s):  
Nitrous Oxide ◽  
Nitrate Reductase ◽  
Oxygen Concentration ◽  
Nitrite Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
A Value ◽  
Nitrite Reductase Activity ◽  
Effect Of Oxygen

Studies on the effect of oxygen on denitrification have shown that denitrification on Pseudomonas nautica 617 can take place in the presence of oxygen. The enzymes associated with denitrification are affected differently with respect to oxygen concentration. Nitrate reductase was less sensitive toward oxygen than nitrite and nitrous oxide reductases. Nitrate reductase activity was completely blocked at an oxygen concentration greater than 4.05 mg/L, compared with 2.15 and 0.25 mg/L for nitrite and nitrous oxide reductases, respectively. After an aerobic–anaerobic shift, nitrate reductase activity remained unchanged whereas the rate of nitrite reductase activity rose to a value only 20% that of the original rate.Key words: denitrification, oxygen, Pseudomonas.

scholarly journals The genes YNI1 and YNR1, encoding nitrite reductase and nitrate reductase respectively in the yeast Hansenula polymorpha, are clustered and co-ordinately regulated

1996 ◽  
Vol 317 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Nélida BRITO ◽  
Julio AVILA ◽  
M. Dolores PEREZ ◽  
Celedonio GONZALEZ ◽  
José M. SIVERIO
Keyword(s):  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Hansenula Polymorpha ◽  
Enzymic Activity ◽  
Wild Type ◽  
Reading Frame ◽  
Dna Library ◽  
Genomic Dna Library ◽  
Nitrate And Nitrite

The nitrite reductase-encoding gene (YNI1) from the yeast Hansenula polymorpha was isolated from a lambda EMBL3 H. polymorpha genomic DNA library, using as a probe a 481 bp DNA fragment from the gene of Aspergillus nidulans encoding nitrite reductase (niiA). An open reading frame of 3132 bp, encoding a putative protein of 1044 amino acids with high similarity with nitrite reductases from fungi, was located by DNA sequencing in the phages λNB5 and λJA13. Genes YNI1 and YNR1 (encoding nitrate reductase) are clustered, separated by 1700 bp. Northern blot analysis showed that expression of YNI1 and YNR1 is co-ordinately regulated; induced by nitrate and nitrite and repressed by sources of reduced nitrogen, even in the presence of nitrate. A mutant lacking nitrite reductase activity was obtained by deletion of the chromosomal copy of YNI1. The mutant does not grow in nitrate or in nitrite; it exhibits a similar level of transcription of YNR1 to the wild type, but the nitrate reductase enzymic activity is only about 50% of the wild type. In the presence of nitrate the Δyni1::URA3 mutant extrudes approx. 24 nmol of nitrite/h per mg of yeast (wet weight), about five times more than the wild type.

La dénitrification chez Bacillus licheniformis

1978 ◽  
Vol 24 (1) ◽  
pp. 45-49 ◽  
Author(s):  
F. Pichinoty ◽  
J.-L. Garcia ◽  
C. Job ◽  
M. Durand
Keyword(s):  
Nitric Oxide ◽  
Gas Chromatography ◽  
Nitrate Reductase ◽  
Electron Donor ◽  
Bacillus Licheniformis ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Cell Extracts ◽  
Nitrite Reductase Activity ◽  
Peptone Medium

The denitrifying capacity of 15 strains of Bacillus licheniformis was evaluated. In general, N2 production by the cultures on complex media containing NO3− is irregular and quite slow and three of the strains never produce gas. Bacillus licheniformis grows rapidly in anaerobiosis on peptone medium containing NO3− which is reduced to NO2−. None of the strains grow in peptone medium with NO2− or N2O as the respiratory substrate, nor do they grow under an atmosphere of 10% NO–90% N2. Denitrification was studied in cell suspensions using gas chromatography. N2O production from NO3− or NO2− is always weak at best; nitric oxide is reduced to N2O at an appreciable rate. All the strains synthesize nitrate reductase A in anaerobiosis when NO3− is present. In cell extracts, nitrite reductase activity is always negligible or nil with tetramethyl-p-phenylenediamine as an electron donor.

Sign in / Sign up

Export Citation Format

Share Document