Modeling electromagnetic field effects in a biochemical reaction: Understanding reactivity inhibition due to the magnetic field

The understanding of electromagnetic effects on biochemical systems is a long standing problem which, in the last decades, raised an increasing interest in the biochemical-biophysical and engineering communities. Possible relevant outcomes of a detailed theoretical comprehension of electromagnetic field-biomolecular systems interaction might be important for biomedical studies, as well as for new technological approaches. The electric field perturbation of a biochemical system is well understood from an atomistic point of view, allowing the development of sophisticated models to describe and predict the biochemical-biophysical transitions induced by the electric field on molecules. On the contrary the magnetic field effects on biomolecular systems are still elusive as a consequence of the extremely limited perturbation energy associated. Although experimental evidences of the magnetic field effects on biochemical reactions have been reported [1] the understanding of the physical-chemical mechanism involved is still a challenge. In this context, we have extended and optimized a theoretical approach based on molecular dynamics (MD) simulations and mixed quantum-classical calculation, the Perturbed Matrix Method (PMM) [2, 3] introduced in the last decade, to explicitly model at atomistic level the effects of the magnetic field on a chemical reaction. In this work we present the results obtained for a prototypical biochemical reaction, i.e. the triplet to singlet relaxation following the electron transfer reaction in the flavin-indole complex, compared to those investigated experimentally [1].