Anisotropic magnetic field effects in the re-oxidation of cryptochrome in the presence of scavenger radicals
Abstract
The avian compass and many other of nature’s magnetoreceptive traits are widely ascribed to the protein cryptochrome. There, magnetosensitivity is thought to emerge as the spin dynamics of radicals in the applied magnetic field enters in competition with their recombination. The first and dominant model makes use of a radical pair. However, recent studies have suggested that magnetosensitivity could be markedly enhanced for a radical triad, the primary radical pair of which undergoes a spin-selective recombination reaction with a third radical. Here, we test the practicality of this supposition for the reoxidation reaction of the reduced FAD cofactor in cryptochrome, which has been implicated with light-independent magnetoreception but appears irreconcilable with the classical radical pair mechanism (RPM). Based on the available realistic cryptochrome structures, we predict the magnetosensitivity of radical triad systems comprising the flavin semiquinone, the superoxide, and a tyrosine or ascorbyl scavenger radical. We consider many hyperfine-coupled nuclear spins, the relative orientation and placement of the radicals, their coupling by the electron–electron dipolar interaction, and spin relaxation in the superoxide radical in the limit of instantaneous decoherence, which have not been comprehensively considered before. We demonstrate that these systems can provide superior magnetosensitivity under realistic conditions, with implications for dark-state cryptochrome magnetoreception and other biological magneto- and isotope-sensitive radical recombination reactions.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 10, 2022
- Source ID
- 10.1063/5.0078115
Entities
People
- Aurélien de la Lande
- Daniel Kattnig
- Fabien Cailliez
- Jean Deviers
Organizations
- Defence Science and Technology Laboratory
- Engineering and Physical Sciences Research Council
- GENCI
- Office of Naval Research Global
- University of Exeter