Proton-Coupled Electron Transfer

Proton-coupled electron transfer (PCET) has a major role in chemistry and biology and its implications for catalysis and energy conversion. Photosynthesis is a spectacular example of PCET in action with the transfer of 24 e- and 24 H+ driven by at least 48 photons. In PCET half reactions, variations in pH influence driving force. Both HAT (H-atom transfer) and EPT (electron-proton transfer) are elementary steps by which PCET reactions can occur. In H-atom transfer (HAT), both the transferring electron and proton come from the same bond in one of the reactants. Multiple Site Electron-Proton Transfer (MS-EPT) is microscopically more complex than electron or proton transfer. It shares with electron transfer requirements for medium and intramolecular reorganization but with the additional complexity of a coupled proton transfer. PCET plays a critical role in many enzymatic pathways that control life such as photosynthesis, respiration, and DNA repair.