Fig 1. Possible Drosophila cryptochrome photocycle.
In the dark, the protein-bound cofactor (FADox) is shown in the oxidized redox state. Light absorption triggers flavin photoreduction [12 – 14] at a rate constant k. Reoxidation to the FADox state occurs spontaneously in the dark at a rate constant kb. Possible changes in C-terminal conformation linked to redox state interconversion are diagrammed [15].