Speaker
Description
The ability of living systems to sense and respond to weak magnetic fields has emerged as a compelling frontier in quantum biology. Blue-light photoreceptor proteins, particularly cryptochromes and LOV domain proteins, provide a unique platform in which light-driven function intersects with spin-dependent quantum dynamics. Upon photoexcitation, these systems generate spin-correlated radical pairs whose evolution is governed by the radical pair mechanism [1–4]. The coherent interconversion between singlet and triplet spin states renders reaction pathways sensitive to weak magnetic interactions, including fields on the order of the Earth’s magnetic field.
In this lecture, it will be discussed how electron and nuclear spin dynamics in these radical pairs give rise to pronounced hyperpolarization effects under biologically relevant conditions [1–4]. Such non-equilibrium spin polarization, typically associated with magnetic resonance methodologies, emerges here intrinsically from the reaction dynamics and encodes information about the underlying spin Hamiltonian. Recent advances in detecting and quantifying these effects using state-of-the-art spectroscopic techniques, bridging concepts from electron spin resonance and nuclear magnetic resonance will be highlighted.
Particular emphasis will be placed on the interplay between molecular structure, spin-selective recombination, and magnetic field effects in shaping observable hyperpolarization signals [4–8]. These findings provide new insight into how weak magnetic interactions can modulate biochemical outcomes through quantum-coherent spin evolution. By integrating experimental results with theoretical modeling, this work advances a unified picture of spin-dependent processes in photoreceptor proteins. It further positions radical pair systems in cryptochromes and LOV domains as model platforms for exploring the limits of quantum coherence in complex biological environments.
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[2] S. Weber, T. Biskup, A. Okafuji, A.R. Marino, T. Berthold, G. Link, K. Hitomi, E.D. Getzoff, E. Schleicher, J.R. Norris, J. Phys. Chem. B, 114 (2010) 14745–14754
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[8] J. Gravell et al., J. Am. Chem. Soc., 147 (2025) 24286–24298