Several redox mechanisms between O2 •-and acidic substrates such as T-705 are known, such as superoxide-facilitated oxidation (SFO), hydrogen-atom transfer involving proton-coupled electron transfer (PCET), , and sequential proton-loss electron transfer. In the SFO mechanism, the initial proton transfer (PT) from the substrate to O2 •-to give a hydroperoxyl radical (HO2 • ) is followed by rapid dismutation to give hydroperoxide (H2O2) and dioxygen (O2).