Flavin Adenine Dinucleotide Photochemistry Is Magnetic Field Sensitive at Physiological pH.

We present time-resolved optical absorption and magnetic field effect data on the photochemistry following blue light excitation of flavin adenine dinucleotide (FAD) in aqueous solution in the pH range 2.3 to 8.0. Effects of closed form conformations of FAD in ground, excited singlet, and radical pair states exhibit significant influence on the observed kinetics and magnetic field dependence and remarkably, magnetic field effects are observed even at physiological pH where the FAD radical pairs are only 75% less magnetic field sensitive than at pH 2.3.