Figure 4.

(a) Distribution of distances from iron to sulfur in an Fe₂S₂ cluster. For each Fe₂S₂ cluster (identified by CSD Refcode) the distances to all four sulfurs within the Fe₂S₂ cluster are shown in blue, while the distances to all four external sulfurs are shown in orange. (b) Distribution of Fe—S distances within Fe₂S₂ modeled in the PDB high-resolution data (<1.5 Å). Typical Fe—S distances are ∼2.2 Å between Fe and sulfurs within the Fe₂S₂ cluster, while typical Fe—S distances are ∼2.3 Å between Fe and external (cysteine) sulfurs.