ABSTRACT
Iron is a transition metal with great chemical versatility found in the rst row of group eight of the periodic table. It displays several redox-, spin-and coordination states accessible in a biological context. Iron-based cofactors play a key role in biological electron transfer by establishing the backbone of the intramolecular wiring for long-distance conduction-be they hemes, as in the hexadecaheme cytochrome from Desulfovibrio (Matias et al., 2002), or Fe-S clusters, as in the peripheral arm of respiratory complex I (Sazanov and Hinchlie, 2006).
