Dynamics-function correlation in photosynthetic water oxidation

Photosystem II (PSII) is a multi-subunit pigment-protein complex responsible for initiating the first step of oxygenic photosynthesis. By acting as a complex molecular machine, PSII uses a series of one-electron photoexcitations to simultaneously drive two-electron reduction reactions and four-electron oxidation reactions. Understanding how PSII orchestrates such a complex set of reactions is important to efforts to develop catalysts for solar fuel production, and the answer lies in part on protein dynamics. While QENS has already been used to link the PSII reduction reactions to protein dynamics, the PSII oxidation reactions have not yet been correlated. As the temperature- and hydration-dependence of the PSII oxidation reactions suggests a dynamics-function correlation, we propose using QENS (combined with complementary EPR experiments) to investigate the role of protein dynamics in the PSII oxidation reactions.