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Nitrous oxide-forming codenitrification catalyzed by cytochrome P450nor
Fei Su1, Naoki Takaya, Hirofumi Shoun
1Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan.
Bioscience, Biotechnology, and Biochemistry
|February 26, 2004
Summary
The fungus Fusarium oxysporum forms nitrous oxide (N2O) through codenitrification. Cytochrome P450nor catalyzes N2O formation from nitric oxide (NO), not nitrite, suggesting NO is the direct substrate.
Area of Science:
- Biochemistry
- Environmental Microbiology
- Fungal Metabolism
Background:
- The denitrifying fungus Fusarium oxysporum catalyzes codenitrification, producing a hybrid nitrous oxide (N2O) species.
- Previous studies indicated nitrite as a substrate for codenitrification in intact cells.
Purpose of the Study:
- To investigate the role of cytochrome P450nor in the codenitrification process.
- To determine the direct substrate for N2O formation catalyzed by cytochrome P450nor.
Main Methods:
- Enzymatic assays using purified cytochrome P450nor.
- Incubation of the enzyme with various nitrogen compounds including nitric oxide (NO), nitrite, azide, and ammonia.
- Analysis of nitrous oxide (N2O) production.
Main Results:
- Cytochrome P450nor catalyzed the formation of N2O from nitric oxide (NO).
- Cytochrome P450nor did not catalyze N2O formation from nitrite, azide, or ammonia.
- These findings suggest that NO, not nitrite, is the direct substrate for codenitrification by intact cells.
Conclusions:
- The direct substrate for codenitrification by Fusarium oxysporum is nitric oxide (NO).
- Nitric oxide (NO) is likely formed from nitrite via a dissimilatory nitrite reductase prior to codenitrification.