Fig. 4.

Proposed photochemical reaction schemes for AtCry and EcPL. The black arrows and species are common to both proteins; the blue and red features refer to AtCry and EcPL, respectively. k_b and k_f are first-order rate constants for electron–hole recombination of RP1 and formation of RP2 from RP1, respectively. Although RP2 in AtCry is here drawn as [FADH^•Trp^•], the protonation state of the Trp radical is not certain. The curved green arrows indicate the coherent, magnetic field-dependent interconversion of the singlet and triplet states of RP1.