Song, S. and Dick, Bernhard and Penzkofer, Alfons and Pokorny, R. and Batschauer, A. and Essen, L. (2006) Absorption and Fluorescence Spectroscopic Characterization of Cryptochrome 3 from Arabidopsis thaliana. Journal of Photochemistry and Photobiology B: Biology 85 (1), pp. 1-16.
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The blue light photoreceptor cryptochrome 3 (cry3) from Arabidopsis thaliana was characterized at room temperature in vitro in aqueous solution by optical absorption and emission spectroscopic studies. The protein non-covalently binds the chromophores flavin adenine dinucleotide (FAD) and N5,N10-methenyl-5,6,7,8-tetrahydrofolate (MTHF). In the dark-adapted state of cry3, the bound FAD is present in the oxidized form (FADox, ca. 38.5%), in the semiquinone form (FADH, ca. 5%), and in the fully reduced neutral form (FADredH2) or fully reduced anionic form (FADredH−, ca. 55%). Some amount of FAD (ca. 1.5%) in the oxidized state remains unbound probably caused by chromophore release and/or denaturation. Förster-type energy transfer from MTHF to FADox is observed. Photo-excitation reversibly modifies the protein conformation causing a slight rise of the MTHF absorption strength and an increase of the MTHF fluorescence efficiency (efficient protein conformation photo-cycle). Additionally there occurs reversible reduction of bound FADox to FADredH2 (or FADredH−, FADox photo-cycle of moderate efficiency), reversible reduction of FADH to FADredH2 (or FADredH−, FADH photo-cycle of high efficiency), and modification of re-oxidable FADredH2 (or FADredH−) to permanent FADredH2 (or FADredH−) with low quantum efficiency. Photo-excitation of MTHF causes the reversible formation of a MTHF species (MTHF′, MTHF photo-cycle, moderate quantum efficiency) with slow recovery to the initial dark state, and also the formation of an irreversible photoproduct (MTHF″).
|Institutions:|| Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Light and Matter) > Prof. Dr. Bernhard Dick |
Physics > Institute of Experimental and Applied Physics > Retired Professors > Group Alfons Penzkofer
|Projects:||Blaulicht-sensitive Photorezeptoren, GRK 640 Sensory photoreceptors in natural and artificial systems|
|Keywords:||Cryptochrome; Arabidopsis thaliana; Cry3; MTHF; FAD; Fluorescence spectroscopy; Absorption spectroscopy; MTHF–FAD interaction; Photo-reduction; Photo-cycle dynamics; Energy transfer|
|Subjects:||500 Science > 530 Physics|
500 Science > 540 Chemistry & allied sciences
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Owner:||Prof. Dr. Bernhard Dick|
|Deposited On:||20 Mar 2007|
|Last Modified:||31 Aug 2012 09:11|