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BP: Fachverband Biologische Physik

BP 10: Computational Biophysics II

BP 10.11: Vortrag

Dienstag, 19. März 2024, 12:30–12:45, H 0112

Understanding the redshift of the absorption spectrum in ClCry4 protein — •Katarina Kretschmer, Anders Frederiksen, and Ilia A. Solov'yov — Universität Oldenburg, Germany

It is still a puzzle how some migratory birds utilize the Earth's magnetic field for biannual migration. The most consistent explanation so far roots on modulation of the biological function of the Cryptochrome 4 (Cry4) protein by external magnetic field. This phenomenon is closely linked with the FAD cofactor that is bound in the protein. The Cry4 protein with the bound FAD cofactor is activated by blue light, absorbed by the FAD cofactor. Through several transfers that trigger radical pair formation in Cry4, the protein can become sensitive to the geomagnetic field. An important redox state of the FAD cofactor is the signaling state, which is present after completion of the different electron transfers inside the protein. Recently it has been possible to crystallize the Cry4 protein from Columbia Livia (ClCry4) with the associated important residues needed for photoreduction. It is the most promising crystallization of the Cry4 protein so far, which also has great similarity with the Cry4 proteins of night migratory birds. The absorption spectrum of the FAD cofactor inside the ClCry4 protein was investigated experimentally in its different redox states during protein's activation. The absorption spectrum of the signaling state demonstrated a redshift if compared to the photoabsorption properties of the FAD cofactor in its signaling state in other Cry proteins. The aim of this study is to understand this redshift by employing the tools of computational microscopy, and in particular the QM/MM approach.

Keywords: DFT; protein; absorption; QM/MM; spectrum