How is N–N bond formation facilitated by P450 NO reductase? A DFT study

The breaking of the very strong NO bond by the enzyme nitric oxide reductase has been explored using density functional theory calculations of a model cluster. A five-step mechanism is proposed. We find a novel mechanism for the formation of the N–N bond in N2O, involving the addition of NO to the intermediate Fe–N(H)OH, followed by a conformational change on a flat potential energy surface to give the strong N–N bond.