... residues and the quinoidmoiety of the ligand, based on the formation of hydrogenbonds. These bonds will, of course, disappear following the double reduction of the RC photocycle and protona-tion of ... organization and the relative energies of the cofactor redox couples, the forward electron transferreactions occur faster than the recombination reactions and therefore, within hundreds of picoseconds, ... doi:10.1046/j.1432-1033.2003.03845.xUnder saturating illumination, the photocycle time scaleis in the order of milliseconds. A key role in the photocycle isplayed by the exchange of the two redox forms of the quinone, between the...