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Involvement of Electron Transfer in the Photoreaction of Zebrafish Cryptochrome‐DASH †
Author(s) -
Zikihara Kazunori,
Ishikawa Tomoko,
Todo Takeshi,
Tokutomi Satoru
Publication year - 2008
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2007.00364.x
Subject(s) - cryptochrome , chemistry , photochemistry , photolyase , electron transfer , flavin group , flavin adenine dinucleotide , chromophore , zebrafish , biophysics , cofactor , biochemistry , biology , dna , enzyme , circadian clock , dna repair , gene
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 (FAD ox ) in the dark. Blue light converts FAD ox to the neutral radical form (FADH ? ). Formed FADH ? is transformed to the fully reduced form FADH 2 (or FADH − ) by successive light irradiation, or reverts to FAD ox . FADH 2 (or FADH − ) reverts to FADH ? or possibly to FAD ox 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.