Fig 3.

Stereo-views (cross-eye) of the binuclear sites of three T. thermophilus cytochrome ba₃ oxidase structures: (A) the crystallized, chemically-reduced (see Fig. 1A-path for spectra, Path-A); (B) the crystallized, X-ray radiation-reduced corresponding to previously reported structures considered at the time to be “oxidized” (see Fig. 1B-path for spectra). One water molecule at the binuclear site (cyan F_o - F_c ‘omit’ map contoured at 4-sigma) is present in Path-B crystals; (C) chemically-reduced, crystallized enzyme (see Fig. 1C-path for spectra). The 2F_o - F_c map illustrates the clean absence of electron density (2 σ) between Fe_a3 and Cu_B in the C-path structure. The anomalous difference maps are contoured at 4-sigma for the Cu_B and Fe_a3.