The reactions of nitrate radical (photochemically generated by the flash photolysis of a mixture of ceric ammonium nitrate and nitric acid) with amino acids are reported. An electron transfer reaction pathway is proposed for phenylalanine and histidine, whereas a hydrogen abstraction pathway is invoked for the other amino acids, based on the magnitudes of the second-order rate constants and the observation of cation radicals. The reactivity of the nitrate radical is compared with that of other oxidizing radicals, such as Cl2+-, CO3+- and SO4+-. The nitrate radical is expected to show a higher reactivity than SO4+- based on their redox couples, but an inverse reactivity relationship is observed and is suggested to be due to the difference in solvation in the transition state.
Venkatachalapathy, B., & Ramamurthy, P. (1996). Reactions of nitrate radical with amino acids in acidic aqueous medium: A flash photolysis investigation. Journal of Photochemistry and Photobiology A: Chemistry, 93(1), 1–5. https://doi.org/10.1016/1010-6030(95)04146-X