A heme- C -containing enzyme complex that exhibits nitrate and nitrite reductase activity from the dissimilatory iron-reducing bacterium Geobacter metallireducens

1999 ◽  
Vol 172 (5) ◽  
pp. 313-320 ◽  
Author(s):  
Francisco Martínez Murillo ◽  
Theresa Gugliuzza ◽  
John Senko ◽  
Partha Basu ◽  
J. F. Stolz
Keyword(s):  
Nitrite Reductase ◽  
Reductase Activity ◽  
Enzyme Complex ◽  
Geobacter Metallireducens ◽  
Nitrite Reductase Activity ◽  
Nitrate And Nitrite

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.

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 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.

scholarly journals 0099. Nitrite reductase activity during sepsis

2014 ◽  
Vol 2 (S1) ◽  
Author(s):  
V Simon ◽  
A Dyson ◽  
M Minnion ◽  
M Feelisch ◽  
M Singer
Keyword(s):  
Nitrite Reductase ◽  
Reductase Activity ◽  
Nitrite Reductase Activity

scholarly journals Nitrite Reductase Activity in Engineered Azurin Variants

2016 ◽  
Vol 55 (9) ◽  
pp. 4233-4247 ◽  
Author(s):  
Steven M. Berry ◽  
Jacob N. Strange ◽  
Erika L. Bladholm ◽  
Balabhadra Khatiwada ◽  
Christine G. Hedstrom ◽  
...  
Keyword(s):  
Nitrite Reductase ◽  
Reductase Activity ◽  
Nitrite Reductase Activity

scholarly journals Increased nitrite reductase activity of fetal versus adult ovine hemoglobin

2009 ◽  
Vol 296 (2) ◽  
pp. H237-H246 ◽  
Author(s):  
Arlin B. Blood ◽  
Mauro Tiso ◽  
Shilpa T. Verma ◽  
Jennifer Lo ◽  
Mahesh S. Joshi ◽  
...  
Keyword(s):  
Nitrite Reductase ◽  
Chronic Hypoxia ◽  
Reductase Activity ◽  
Fetal Hemoglobin ◽  
Nitrite Reduction ◽  
No Production ◽  
Low Oxygen ◽  
Nitrite Reductase Activity ◽  
Adult Hemoglobin ◽  
Severe Ischemia

Growing evidence indicates that nitrite, NO2−, serves as a circulating reservoir of nitric oxide (NO) bioactivity that is activated during physiological and pathological hypoxia. One of the intravascular mechanisms for nitrite conversion to NO is a chemical nitrite reductase activity of deoxyhemoglobin. The rate of NO production from this reaction is increased when hemoglobin is in the R conformation. Because the mammalian fetus exists in a low-oxygen environment compared with the adult and is exposed to episodes of severe ischemia during the normal birthing process, and because fetal hemoglobin assumes the R conformation more readily than adult hemoglobin, we hypothesized that nitrite reduction to NO may be enhanced in the fetal circulation. We found that the reaction was faster for fetal than maternal hemoglobin or blood and that the reactions were fastest at 50–80% oxygen saturation, consistent with an R-state catalysis that is predominant for fetal hemoglobin. Nitrite concentrations were similar in blood taken from chronically instrumented normoxic ewes and their fetuses but were elevated in response to chronic hypoxia. The findings suggest an augmented nitrite reductase activity of fetal hemoglobin and that the production of nitrite may participate in the regulation of vascular NO homeostasis in the fetus.

scholarly journals Inhibition of tobacco nitrite reductase activity by expression of antisense RNA.

1992 ◽  
Vol 2 (4) ◽  
pp. 559-569 ◽  
Author(s):  
H Vaucheret ◽  
J Kronenberger ◽  
A Lepingle ◽  
F Vilaine ◽  
JP Boutin ◽  
...  
Keyword(s):  
Nitrite Reductase ◽  
Antisense Rna ◽  
Reductase Activity ◽  
Nitrite Reductase Activity

scholarly journals The human B12 trafficking protein CblC processes nitrocobalamin

2020 ◽  
Vol 295 (28) ◽  
pp. 9630-9640 ◽  
Author(s):  
Romila Mascarenhas ◽  
Zhu Li ◽  
Carmen Gherasim ◽  
Markus Ruetz ◽  
Ruma Banerjee
Keyword(s):  
Nitrite Reductase ◽  
Reductase Activity ◽  
Methylmalonic Aciduria ◽  
Axial Ligand ◽  
Vitamin B ◽  
Early Step ◽  
Trafficking Pathway ◽  
Nitrite Reductase Activity ◽  
Futile Cycling ◽  
Thiol Oxidase

In humans, cobalamin or vitamin B12 is delivered to two target enzymes via a complex intracellular trafficking pathway comprising transporters and chaperones. CblC (or MMACHC) is a processing chaperone that catalyzes an early step in this trafficking pathway. CblC removes the upper axial ligand of cobalamin derivatives, forming an intermediate in the pathway that is subsequently converted to the active cofactor derivatives. Mutations in the cblC gene lead to methylmalonic aciduria and homocystinuria. Here, we report that nitrosylcobalamin (NOCbl), which was developed as an antiproliferative reagent, and is purported to cause cell death by virtue of releasing nitric oxide, is highly unstable in air and is rapidly oxidized to nitrocobalamin (NO2Cbl). We demonstrate that CblC catalyzes the GSH-dependent denitration of NO2Cbl forming 5-coordinate cob(II)alamin, which had one of two fates. It could be oxidized to aquo-cob(III)alamin or enter a futile thiol oxidase cycle forming GSH disulfide. Arg-161 in the active site of CblC suppressed the NO2Cbl-dependent thiol oxidase activity, whereas the disease-associated R161G variant stabilized cob(II)alamin and promoted futile cycling. We also report that CblC exhibits nitrite reductase activity, converting cob(I)alamin and nitrite to NOCbl. Finally, the denitration activity of CblC supported cell proliferation in the presence of NO2Cbl, which can serve as a cobalamin source. The newly described nitrite reductase and denitration activities of CblC extend its catalytic versatility, adding to its known decyanation and dealkylation activities. In summary, upon exposure to air, NOCbl is rapidly converted to NO2Cbl, which is a substrate for the B12 trafficking enzyme CblC.

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