High Field Switching of J-Resonance Through a Kinetically Competent Spin-Correlated Radical-Pair Intermediate in the Cooperative Action of B6, B12 and Lysine 5,6-Aminomutase
陳俊儒1, 柯學初1*
1Physics, National Dong Hwa University, Hualien, Taiwan
* Presenter:柯學初, email:ke@gms.ndhu.edu.tw
Environmental magnetic field is beneficial to migratory birds navigation and by no means proven has obvious adverse human health effects. One of the continuing challenges in how magnetic field may impact biology is the lack of field-sensitive examples for investigation. We show that the chemical reaction of B12 and B6 co-dependent lysine 5,6-aminomutase proceeds via spin-correlated radical-pair intermediates and is magnetic field dependent. The 5′-deoxyadenosyl radical from B12 abstracts a C5(H) from substrate to yield a triplet {cob(II)alamin-substrate} radical-pair. Intersystem crossing to singlet state occurs at 8000 gauss. Spin conserved H-back-transfer yields a singlet {cob(II)alamin-5′-deoxyadenosyl} radical-pair for spin selective recombination to adenosylcobalamin, decreasing the enzyme catalytic efficiency by 18%. The pronounced high field level crossing characteristic through an immobilized radical-pair with constant exchange interaction is unprecedented in biology. Mechanism of the cooperative action of B6, B12 and lysine 5,6-aminomutase will be proposed.

Keywords: enzyme catalysis, free radicals, magnetic field effect, EPR