Reaction Mechanism
The mechanism of action has still not been entirely deduced, however, the leading theory suggests that the conversion is carried out through a series of redox reactions involving iron centers as shown in the series of half reactions below:
| Step | Reaction |
|---|---|
| FAD reduction | NAD(P)H + FAD + H+ → NAD(P)+ + FADH2 |
| Iron reduction 1 | FADH2 + Fe3+ → Fe2+ + FADH + H+ |
| Iron Reduction 2 | FADH + Fe3+ → FAD + Fe2+ + H+ |
| O2 Binding | Fe2+ + O2 → Fe3+(O2-) |
| NO dioxygenation | Fe3+(O2-) + NO → Fe3+ + NO3- |
Another theory developed more recently (2009) suggests that a NO dioxygenase activity could also proceed through phenolic nitration via a putative heme-peroxynitrite intermediate.
The most well studied NO dioxygenase is flavohemoglobin (flavoHb), shown to the right: Studies have shown that flavohemoglobins are induced by NO, nitrite, nitrate, and NO-releasing agents in various bacteria and fungi. Additionally, flavoHbs have been shown to protect bacteria, yeast, and Dictyostelium discoideum against growth inhibition and damage mediated via NO.
Read more about this topic: Nitric Oxide Dioxygenase
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