Scheme 4.

Formation of the Neutral Sugar Radical (C_5′^•) through a Proton Coupled Electron Transfer Mechanism in 2′-Deoxyguanosine radical cation (dG^•+).^a

^aThe proton transfers from C_5′ to N₇ of guanine through waters and results in electron transfer from C_5′ to guanine yielding the product, (dG(^•C_5′, N₇-H⁺) + 7H₂O). (Figure reproduced with permission from ref. 228. Copyright 2009 American Chemical Society.)