EPR studies of the oxygen-evolving complex reveal a light-adaption process in Photosystem II
Photosystem II utilizes solar energy to drive electrons from the Mn cluster at the lumenal side to the quinone at the stromal side of the thylakoid membrane. The source of electrons is H2O, which is split to oxygen by the OEC. The water-splitting process involves cycling of the Mn-cluster through four semi-stable oxidation states, termed the S0, S1, S2, and S3 states. The OEC can be trapped in the