SKM 2023 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 11: Poster Session I
BP 11.42: Poster
Dienstag, 28. März 2023, 12:30–15:30, P1
Tracking the Electron Transfer Cascade in European Robin Cryptochrome 4 Mutants — •Daniel Timmer1, Anders Frederiksen1, Daniel C. Lünemann1, Anitta R. Thomas1, Jingjing Xu1, Rabea Bartölke1, Jessica Schmidt1, Tomas Kubar2, Antonietta De Sio1, Ilia A. Solov'yov1, Henrik Mouritsen1, and Christoph Lienau1 — 1University of Oldenburg, Germany — 2Karlsruhe Institute of Technology, Germany
The ability of some birds to sense weak earth-strength magnetic fields for navigation is thought to rely on the quantum mechanical radical pair (RP) mechanism [1]. Here, cryptochrome proteins, located in the birds retina, can undergo consecutive electron transfers after blue light photo-excitation of a bound flavin chromophore with a nearby chain of four tryptophan amino acid residues. This leads to the formation of a long-lived RP, which can interconvert between the singlet and triplet state due to hyperfine interactions. Spin-selective signaling state populations can eventually be influenced via a weak external magnetic field [1]. Using pump-probe spectroscopy on wildtype cryptochrome protein of the European robin and a series of mutants, where we selectively blocked the electron transfer along the chain with redox-inactive phenylalanine, we are able to track RP formation step by step and extract the electron transfer times and yields [1]. Our experimental study is supported by theoretical modeling of the electron transfer cascade using a mixed quantum mechanical/molecular mechanical approach. [1]: Xu, Jingjing, et al., Nature 594.7864, 535-540 (2021). [2]: Timmer, Daniel, et al., arXiv preprint arXiv:2205.10393 (2022).