Figure 1.

The structures of the Rieske [2Fe-2S] cluster site in R. sphaeroides ISP (A) (taken from 1rie.pdb but in R. sphaeroides numbering [Guergova-Kuras et al. 2000]) and S. tokodaii SDX (B) (Uchiyama et al. 2004; T. Iwasaki, T. Uchiyama, A. Kounosu, and T. Kumasaka, unpubl.) showing the two targeted residues of interest and the four ligand residues. The proline-rich loop region was omitted for clarity. (C) The hydrogen bond orientation used for the preliminary normal mode calculation, as defined by ϕ between the Fe-S-C (or Fe-S-Fe) plane and S–HO bond; and θ of the S–HO bond within the Fe-S-C (or Fe-S-Fe) plane.