The redox couple of the cytochrome c cyanide complex: the contribution of heme iron ligation to the structural stability, chemical reactivity, and physiological behavior of horse cytochrome c.

Contrary to most heme proteins, ferrous cytochrome c does not bind ligands such as cyanide and CO. In order to quantify this observation, the redox potential of the ferric/ferrous cytochrome c-cyanide redox couple was determined for the first time by cyclic voltammetry. Its E0' was -240 mV versus SHE, equivalent to -23.