title: Magnetic field effects as a result of the radical pair mechanism are unlikely in redox enzymes.
abstract: Environmental exposure to electromagnetic fields is potentially carcinogenic. The radical pair mechanism is considered the most feasible mechanism of interaction between weak magnetic fields encountered in our environment and biochemical systems. Radicals are abundant in biology, both as free radicals and reaction intermediates in enzyme mechanisms. The catalytic cycles of some flavin-dependent enzymes are either known or potentially involve radical pairs. Here, we have investigated the magnetic field sensitivity of a number of flavoenzymes with important cellular roles. We also investigated the magnetic field sensitivity of a model system involving stepwise reduction of a flavin analogue by a nicotinamide analogue-a reaction known to proceed via a radical pair. Under the experimental conditions used, magnetic field sensitivity was not observed in the reaction kinetics from stopped-flow measurements in any of the systems studied. Although widely implicated in radical pair chemistry, we conclude that thermally driven, flavoenzyme-catalysed reactions are unlikely to be influenced by exposure to external magnetic fields.
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, Manchester, UK Faculty of Life Sciences, University of Manchester, Manchester, UK.
authors.forename: Hanan L
authors.initials: HL
authors.lastname: Messiha
authors.affiliation: Department of Biochemistry and Centre for Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Thanyaporn
authors.initials: T
authors.lastname: Wongnate
authors.affiliation: Department of Biochemistry and Centre for Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Pimchai
authors.initials: P
authors.lastname: Chaiyen
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, Manchester, UK Photon Science Institute and School of Chemistry, University of Manchester, Manchester, UK alex.jones-2@manchester.ac.uk.
authors.forename: Alex R
authors.initials: AR
authors.lastname: Jones
authors.affiliation: Manchester Institute of Biotechnology, University of Manchester, Manchester, UK Faculty of Life Sciences, University of Manchester, Manchester, UK nigel.scrutton@manchester.ac.uk.
authors.forename: Nigel S
authors.initials: NS
authors.lastname: Scrutton
mesh_terms: D001487:Basidiomycota / Q000201:enzymology*; D002237:Carbohydrate Dehydrogenases / Q000737:chemistry*; D004138:Dinitrocresols / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry*; D007700:Kinetics; D060526:Magnetic Fields; D008956:Models, Chemical; D010084:Oxidation-Reduction
chemical_list: D004138:Dinitrocresols; D005656:Fungal Proteins; C024132:4,6-dinitro-o-cresol; D002237:Carbohydrate Dehydrogenases; C022489:pyranose oxidase
keywords: environmental magnetic fields; flavoproteins; hydride transfer; magnetic field effects; radical pair mechanism