Electrocatalytic Reductions of Nitrite, Nitric Oxide, and Nitrous Oxide by Thermophilic Cytochrome P450 CYP119 in Film-Modified Electrodes and an Analytical Comparison of Its Catalytic Activities with Myoglobin

2004 ◽  
Vol 126 (15) ◽  
pp. 4934-4942 ◽  
Author(s):  
Chad E. Immoos ◽  
Ju Chou ◽  
Mekki Bayachou ◽  
Emek Blair ◽  
John Greaves ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Cytochrome P450 ◽  
Modified Electrodes ◽  
Analytical Comparison ◽  
Catalytic Activities

scholarly journals Fungal denitrification and nitric oxide reductase cytochrome P450nor

2012 ◽  
Vol 367 (1593) ◽  
pp. 1186-1194 ◽  
Author(s):  
Hirofumi Shoun ◽  
Shinya Fushinobu ◽  
Li Jiang ◽  
Sang-Wan Kim ◽  
Takayoshi Wakagi
Keyword(s):  
Nitric Oxide ◽  
Phylogenetic Analysis ◽  
Electron Transfer ◽  
Nitrous Oxide ◽  
Cytochrome P450 ◽  
Nicotinamide Adenine Dinucleotide ◽  
Anaerobic Respiration ◽  
Nitric Oxide Reductase ◽  
Nitrogen Donor ◽  
Mitochondrial Origin

We have shown that many fungi (eukaryotes) exhibit distinct denitrifying activities, although occurrence of denitrification was previously thought to be restricted to bacteria (prokaryotes), and have characterized the fungal denitrification system. It comprises NirK (copper-containing nitrite reductase) and P450nor (a cytochrome P450 nitric oxide (NO) reductase (Nor)) to reduce nitrite to nitrous oxide (N 2 O). The system is localized in mitochondria functioning during anaerobic respiration. Some fungal systems further contain and use dissimilatory and assimilatory nitrate reductases to denitrify nitrate. Phylogenetic analysis of nirK genes showed that the fungal-denitrifying system has the same ancestor as the bacterial counterpart and suggested a possibility of its proto-mitochondrial origin. By contrast, fungi that have acquired a P450 from bacteria by horizontal transfer of the gene, modulated its function to give a Nor activity replacing the original Nor with P450nor. P450nor receives electrons directly from nicotinamide adenine dinucleotide to reduce NO to N 2 O. The mechanism of this unprecedented electron transfer has been extensively studied and thoroughly elucidated. Fungal denitrification is often accompanied by a unique phenomenon, co-denitrification, in which a hybrid N 2 or N 2 O species is formed upon the combination of nitrogen atoms of nitrite with a nitrogen donor (amines and imines). Possible involvement of NirK and P450nor is suggested.

Emissions of nitrous oxide and nitric oxide associated with the decomposition of arable crop residues on a sandy loam soil in Eastern England

Agronomie ◽  
2002 ◽  
Vol 22 (7-8) ◽  
pp. 731-738 ◽  
Author(s):  
Roland Harrison ◽  
Sharon Ellis ◽  
Roy Cross ◽  
James Harrison Hodgson
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Crop Residues ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
Arable Crop ◽  
Loam Soil

The complete denitrification pathway of the symbiotic, nitrogen-fixing bacterium Bradyrhizobium japonicum

2005 ◽  
Vol 33 (1) ◽  
pp. 141-144 ◽  
Author(s):  
E.J. Bedmar ◽  
E.F. Robles ◽  
M.J. Delgado
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Bradyrhizobium Japonicum ◽  
Mutational Analysis ◽  
Control Level ◽  
Gene Clusters ◽  
Alternative Form ◽  
Nitrate Respiration ◽  
Regulatory Cascade ◽  
Denitrification Genes

Denitrification is an alternative form of respiration in which bacteria sequentially reduce nitrate or nitrite to nitrogen gas by the intermediates nitric oxide and nitrous oxide when oxygen concentrations are limiting. In Bradyrhizobium japonicum, the N2-fixing microsymbiont of soya beans, denitrification depends on the napEDABC, nirK, norCBQD, and nosRZDFYLX gene clusters encoding nitrate-, nitrite-, nitric oxide- and nitrous oxide-reductase respectively. Mutational analysis of the B. japonicum nap genes has demonstrated that the periplasmic nitrate reductase is the only enzyme responsible for nitrate respiration in this bacterium. Regulatory studies using transcriptional lacZ fusions to the nirK, norCBQD and nosRZDFYLX promoter region indicated that microaerobic induction of these promoters is dependent on the fixLJ and fixK2 genes whose products form the FixLJ–FixK2 regulatory cascade. Besides FixK2, another protein, nitrite and nitric oxide respiratory regulator, has been shown to be required for N-oxide regulation of the B. japonicum nirK and norCBQD genes. Thus nitrite and nitric oxide respiratory regulator adds to the FixLJ–FixK2 cascade an additional control level which integrates the N-oxide signal that is critical for maximal induction of the B. japonicum denitrification genes. However, the identity of the signalling molecule and the sensing mechanism remains unknown.

scholarly journals Emissions of Nitrous Oxide and Nitric Oxide from Soils of Native and Exotic Ecosystems of the Amazon and Cerrado Regions of Brazil

2001 ◽  
Vol 1 ◽  
pp. 312-319 ◽  
Author(s):  
Eric A. Davidson ◽  
Mercedes M.C. Bustamante ◽  
Alexandre de Siqueira Pinto
Keyword(s):  
Nitric Oxide ◽  
Land Use ◽  
Nitrous Oxide ◽  
Photochemical Reactions ◽  
N2o Emissions ◽  
Secondary Forests ◽  
Soil Emissions ◽  
Amazonian Forests ◽  
The Impact ◽  
No Emissions

This paper reviews reports of nitrous oxide (N2O) and nitric oxide (NO) emissions from soils of the Amazon and Cerrado regions of Brazil. N2O is a stable greenhouse gas in the troposphere and participates in ozone-destroying reactions in the stratosphere, whereas NO participates in tropospheric photochemical reactions that produce ozone. Tropical forests and savannas are important sources of atmospheric N2O and NO, but rapid land use change could be affecting these soil emissions of N oxide gases. The five published estimates for annual emissions of N2O from soils of mature Amazonian forests are remarkably consistent, ranging from 1.4 to 2.4 kg N ha–1 year–1, with a mean of 2.0 kg N ha–1 year–1. Estimates of annual emissions of NO from Amazonian forests are also remarkably similar, ranging from 1.4 to 1.7 kg N ha–1 year–1, with a mean of 1.5 kg N ha–1 year–1. Although a doubling or tripling of N2O has been observed in some young (<2 years) cattle pastures relative to mature forests, most Amazonian pastures have lower emissions than the forests that they replace, indicating that forest-topasture conversion has, on balance, probably reduced regional emissions slightly (<10%). Secondary forests also have lower soil emissions than mature forests. The same patterns apply for NO emissions in Amazonia. At the only site in Cerrado where vegetation measurements have been made N2O emissions were below detection limits and NO emissions were modest (~0.4 kg N ha–1 year–1). Emissions of NO doubled after fire and increased by a factor of ten after wetting dry soil, but these pulses lasted only a few hours to days. As in Amazonian pastures, NO emissions appear to decline with pasture age. Detectable emissions of N2O have been measured in soybean and corn fields in the Cerrado region, but they are modest relative to fluxes measured in more humid tropical agricultural regions. No measurements of NO from agricultural soils in the Cerrado region have been made, but we speculate that they could be more important than N2O emissions in this relatively dry climate. While a consistent pattern is emerging from these studies in the Amazon region, far too few data exist for the Cerrado region to assess the impact of land use changes on N oxide emissions.

scholarly journals Characterization of the Mechanism of Cytochrome P450 Reductase-Cytochrome P450-mediated Nitric Oxide and Nitrosothiol Generation from Organic Nitrates

2006 ◽  
Vol 281 (18) ◽  
pp. 12546-12554 ◽  
Author(s):  
Haitao Li ◽  
Xiaoping Liu ◽  
Hongmei Cui ◽  
Yeong-Renn Chen ◽  
Arturo J. Cardounel ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cytochrome P450 ◽  
Organic Nitrates ◽  
Cytochrome P450 Reductase ◽  
P450 Reductase
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