Mechanism of Photosynthetic Oxygen Production

This chapter deals with the mechanism of photosynthetic water oxidation that leads to O2 formation in Photosystem II (PS II). After a brief introduction to the structure and function of the PS II complex, the S-state cycle (Kok model) is outlined and the structure and oxidation states of the catalytic Mn4OxCa complex are summarized. We then cover in detail the current information concerning substrate water binding and consider energetic and kinetic aspects of photosynthetic water oxidation. On that basis, we discuss several recent mechanistic proposals for O-O bond formation in PS II and summarize our current perceptions in a novel mechanistic proposal for photosynthetic water oxidation.