A low-redox potential heme in the dinuclear center of bacterial nitric oxide reductase: implications for the evolution of energy-conserving heme-copper oxidases

The action of bacterial nitric oxide reductase (NOR) on nitric oxide and nitrous oxide plays an integral role in the completion of the two-electron process undergone by these compounds. NOR is considered a diverged member of the heme-copper oxidase group since it exhibits a distinct electronic absorption spectrum. Experimental data derived from a Pavacocus denitrificans strain suggest that the oxygen reducing activity manifested by heme-copper oxidases is significantly attributed to the substitution of copper for non-heme iron in the dinuclear center.