title: Involvement of electron transfer in the photoreaction of zebrafish Cryptochrome-DASH.
abstract: 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.
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Zikihara
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Todo
authors.forename: Satoru
authors.initials: S
authors.lastname: Tokutomi
mesh_terms: D000818:Animals; D056931:Cryptochromes; D003624:Darkness; D004579:Electron Transport; D005420:Flavoproteins / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*; D008027:Light; D010786:Photoreceptor Cells / Q000378:metabolism; D013053:Spectrophotometry; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D056931:Cryptochromes; D005420:Flavoproteins; D029961:Zebrafish Proteins; C504783:cryptochrome DASH, zebrafish