Radical intermediates generated in the reactions of L-arginine with hydroxyl radical and sulfate radical anion: A pulse radiolysis study

Reactions of L-arginine (Arg) with hydroxyl radical (·OH) and sulfate radical anion (SO4-·) were kinetically investigated by the pulse radiolysis technique. Hydrogen abstraction from Arg by ·OH afforded redox chemically oxidizing, neutral, and reducing carbon-centered Arg radicals. Kinetic properties of the radicals indicated that the reducing species might include the δ-C-centered Arg radical and CO2 radical anion. Similar transient spectra were observed in the SO4-· reaction with Arg, suggesting direct oxidation at the guanidino group is less likely