Fig. 2.

A schematic showing the sequence of electron transfer reactions occurring in the reaction mixture. Photoactivation of Ru₂C results in reduction of CcO (Cu_A → heme a → oxoferryl heme a₃/Cu_B). The oxidized Ru₂C is reduced by aniline, which releases a proton. Oxidized aniline, in turn, is rereduced by 3CP, which is oxidized without proton release. The boxed X^–H⁺ and Y^–H⁺ represent the two internal proton donors, one of which is Glu-242 (bovine).