Effect of content of the oxidized-type structure on the average B-factor values of the refined structures of both the oxidized- and reduced-type structures for the monomer A. The effect is shown by the difference between the average B-factor values of the refined oxidized- and reduced-type structures (ΔB), defined as follows: ΔB = average B-factor value of the refined reduced-type structure – average B-factor value of the refined oxidized-type structure. The ΔB values, determined at various content of the reduced-type structure, are plotted against the content of the oxidized-type structure included, for the hydroxyfarnesyl ethyl group of heme a in green, and for residues 48 to 55 and 380 to 385, in blue and red plots, respectively. A–D, the ΔB plots for the fully reduced form, IO10, IO20, and IO80, respectively.