Quantifying electron transfer reactions in biological systems: what interactions play the major role?

Emil Sjulstok, Jogvan Magnus Haugaard Olsen, Ilia A. Solov'yov
Scientific Reports
Various biological processes involve the conversion of energy into forms that are usable for chemical transformationsand are quantum mechanical in nature. Such processes involve light absorption, excited electronic states formation, excitation
energy transfer, electrons and protons tunnelling which for example occur in photosynthesis, cellular respiration, DNA repair
and possibly magnetic field sensing. Quantum biology uses computation to model biological interactions in light of quantum
mechanical effects and has primarily developed over the past decade as a result of convergence between quantum physics and biology.
In this paper we consider electron transfer in biological processes, from a theoretical view-point; namely in terms of quantum
mechanical and semi-classical models. We systematically characterize the interactions between the moving electron and its
biological environment to deduce the driving force for the electron transfer reaction and to establish those interactions that
play the major role in propelling the electron. The suggested approach is seen as a general recipe to treat electron transfer
events in biological systems computationally, and we utilize it to describe specifically the electron transfer reactions in
Arabidopsis thaliana cryptochrome — a signaling photoreceptor protein that became attractive recently due to
its possible function as a biological magnetoreceptor.