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Direct Observation of a Photoinduced Radical Pair in a Cryptochrome Blue-Light Photoreceptor

Authors

  • Till Biskup,

    1. Department of Physics, Free University Berlin (Germany)
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  • Erik Schleicher Dr.,

    1. Institute of Physical Chemistry, Faculty of Chemistry, Pharmacy and Earth Sciences, Albert-Ludwigs-University, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-203-6222
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  • Asako Okafuji,

    1. Institute of Physical Chemistry, Faculty of Chemistry, Pharmacy and Earth Sciences, Albert-Ludwigs-University, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-203-6222
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  • Gerhard Link Dr.,

    1. Institute of Physical Chemistry, Faculty of Chemistry, Pharmacy and Earth Sciences, Albert-Ludwigs-University, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-203-6222
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  • Kenichi Hitomi Dr.,

    1. Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA (USA)
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  • Elizabeth D. Getzoff Prof.,

    1. Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA (USA)
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  • Stefan Weber Prof. Dr.

    1. Institute of Physical Chemistry, Faculty of Chemistry, Pharmacy and Earth Sciences, Albert-Ludwigs-University, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-203-6222
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  • This work was supported by the Deutsche Forschungsgemeinschaft (Sfb-498, project A2, and FOR-526), the U.S. National Institutes of Health (Grant R01 GM37684 to E.D.G.), and the Skaggs Institute of Chemical Biology (fellowship to K.H.). We thank J. R. Norris (University of Chicago) and R. Bittl (Free University Berlin) for helpful discussions.

Abstract

original image

Compass component: Blue-light excitation of the photoreceptor cryptochrome generates a transient radical pair by electron transfer from a tryptophan (Trp) at the surface to the flavin cofactor in the center of the protein (see picture; FAD=flavin adenine dinucleotide). Simulated EPR spectra show that the electronic coupling parameters of these radical pairs are suitable for animal magnetoreception.

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