A model of an enzyme reaction cycle that includes the generation of a transient spin-correlated radical pair state is discussed. The recombination yield of the radical pair state is altered by external magnetic fields (radical pair mechanism). In this theoretical study, the response behavior of the enzyme to pulsed magnetic fields as well as combinations of static and sinusoidally oscillating magnetic fields is investigated by using an approach that combines enzyme kinetics with magnetic field-sensitive spin kinetics. Calculations show that the enzyme behaves like a frequency sensor that is responsive at lower field frequencies but less responsive at frequencies that are faster than the time scales inherent to the kinetic properties of the reaction cycle. There is a characteristic transition region in the frequency domain that reflects the enzyme’s relaxation behavior to time-dependent external perturbations. The transition region is characterized by using methods based on the theory of externally driven systems, including Floquet theory and the calculation of correlation functions. Model simulations suggest that time-dependent magnetic fields could be used as a tool to study the response behavior of magnetic field-sensitive enzymes.
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1 October 1997
Research Article|
October 01 1997
Low-frequency-dependent effects of oscillating magnetic fields on radical pair recombination in enzyme kinetics
C. Eichwald;
C. Eichwald
Department of Radiation Oncology, Biolelectromagnetics Laboratory, School of Medicine—AO38, Stanford University, Stanford, California 94305-5124
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J. Walleczek
J. Walleczek
Department of Radiation Oncology, Biolelectromagnetics Laboratory, School of Medicine—AO38, Stanford University, Stanford, California 94305-5124
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J. Chem. Phys. 107, 4943–4950 (1997)
Article history
Received:
December 16 1996
Accepted:
June 27 1997
Citation
C. Eichwald, J. Walleczek; Low-frequency-dependent effects of oscillating magnetic fields on radical pair recombination in enzyme kinetics. J. Chem. Phys. 1 October 1997; 107 (13): 4943–4950. https://doi.org/10.1063/1.474858
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