Calculations of Earth-strength steady and oscillating magnetic field effects in coenzyme B12 radical pair systems

Abstract

This paper uses electron paramagnetic resonance data for radical pair systems in several coenzyme B12-dependent enzymes and calculates effects of Earth-strength steady and oscillating magnetic fields on their singlet-to-triplet yields via the radical pair mechanism. Energy level repulsions and the state mixing that they induce are found to be very important for determining overall sizes of effects and lower bounds on oscillating-field frequencies that can cause effects in such systems. B12 and similar systems with nearly axial zero-field spin Hamiltonians, dominated by terms over 100 times larger than Zeeman terms due to Earth-strength steady fields, if under relatively immobile conditions of long lifetime, slow molecular tumbling and slow spin relaxation, may be useful as biological sensors of both steady and oscillating fields that occur in nature, since the yields calculated show sensitivity to steady field strength (even after powder averaging) and orientation and undergo steady-field-dependent shifts...