Analyses of donor–acceptor distance-dependent rates of photo-induced electron transfer in flavoproteins with three kinds of electron transfer theories

Reported donor–acceptor distance-dependent rates of photo-induced electron transfer from tryptophan (Trp), tyrosine (Tyr), and benzoate (Bz) to the excited isoalloxazine in ten flavoprotein systems were analyzed with three kinds of electron transfer theories by Marcus, by Bixon and Jortner, and also by Kakitani, Yoshimori, and Mataga. Average donor–acceptor distances that were obtained from X-ray structures of flavoproteins were used for the analysis, rather than the edge-to-edge distance. The observed photo-induced electron transfer rates were best reproduced by the Kakitani, Yoshimori, and Mataga theory.