Diverse NO reduction by Halomonas halodenitrificans nitric oxide reductase

Reduction of the four Fe centers is not required to initiate the reaction of the Halomonas halodenitrificans nitric oxide reductase (NOR) based on the facts that NOR in the form that ferric heme b3 and non-heme iron (FeB) are not bridged and/or the interaction between them is weakened and reversibly binds NO molecules, and that NOR in the form that only heme b3 is oxidized reacts with NO molecules.