§Current address: Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
Involvement of Electron Transfer in the Photoreaction of Zebrafish Cryptochrome-DASH†
Article first published online: 20 MAY 2008
© 2008 The Authors. Journal Compilation. The American Society of Photobiology
Photochemistry and Photobiology
Volume 84, Issue 4, pages 1016–1023, July/August 2008
How to Cite
Zikihara, K., Ishikawa, T., Todo, T. and Tokutomi, S. (2008), Involvement of Electron Transfer in the Photoreaction of Zebrafish Cryptochrome-DASH. Photochemistry and Photobiology, 84: 1016–1023. doi: 10.1111/j.1751-1097.2007.00364.x
†This invited paper is part of the Symposium-in-Print: Photoreceptors and Signal Transduction.
- Issue published online: 9 JUL 2008
- Article first published online: 20 MAY 2008
- Received 7 December 2007, accepted 10 March 2008
Photoreaction of a blue-light photoreceptor Cryptochrome-DASH (Cry-DASH), a new member of the Cryptochrome family, from zebrafish was studied by UV–visible absorption spectroscopy in aqueous solutions at 293 K. Zebrafish Cry-DASH binds two chromophores, a flavin adenine dinucleotide (FAD) and a N5,N10-methenyl-5,6,7,8-tetrahydrofolate (MTHF) noncovalently. The bound FAD exists in the oxidized form (FADox) in the dark. Blue light converts FADox to the neutral radical form (FADH?). Formed FADH? is transformed to the fully reduced form FADH2 (or FADH−) by successive light irradiation, or reverts to FADox. FADH2 (or FADH−) reverts to FADH? or possibly to FADox directly. The effect of dithiothreitol suggests a possible electron transfer between FAD in zebrafish Cry-DASH and reductants in the external medium. This is the first report on the photoreaction pathway and kinetics of a vertebrate Cry-DASH family protein.