Fig. 1. Schematic representation of FeMo-cofactor of Mo-nitrogenase, FeV-cofactor of V-nitrogenase, and proposed FeFe-cofactor in Fe-nitrogenase. The overall spin state of each resting state cofactor, the redox state, and proposed spin state of the Mo, V, and Fe atoms at the same position in the corresponding cofactor are highlighted. The amino acid and R-homocitrate ligands are not shown.
