Decrypting Cryptochrome: Revealing the Molecular Identity of the Photoactivation Reaction

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• 作者：Ilia A. Solov鈥檡ov ; Tatiana Domratcheva ; Abdul Rehaman Moughal Shahi ; Klaus Schulten
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：October 31, 2012
• 年：2012
• 卷：134
• 期：43
• 页码：18046-18052
• 全文大小：462K
• 年卷期：v.134,no.43(October 31, 2012)
• ISSN：1520-5126

文摘

Migrating birds fly thousands of miles or more, often without visual cues and in treacherous winds, yet keep direction. They employ for this purpose, apparently as a powerful navigational tool, the photoreceptor protein cryptochrome to sense the geomagnetic field. The unique biological function of cryptochrome supposedly arises from a photoactivation reaction involving radical pair formation through electron transfer. Radical pairs, indeed, can act as a magnetic compass; however, the cryptochrome photoreaction pathway is not fully resolved yet. To reveal this pathway and underlying photochemical mechanisms, we carried out a combination of quantum chemical calculations and molecular dynamics simulations on plant (Arabidopsis thaliana) cryptochrome. The results demonstrate that after photoexcitation a radical pair forms, becomes stabilized through proton transfer, and decays back to the protein鈥檚 resting state on time scales allowing the protein, in principle, to act as a radical pair-based magnetic sensor. We briefly relate our findings on A. thaliana cryptochrome to photoreaction pathways in animal cryptochromes.