Preface for Special Issue of Photosynthesis Research “Photosynthetic Water Oxidation”

Abstract

Oxygenic photosynthesis is vital to the maintenance of heterotrophic, aerobic life on Earth. This process supplies both energy, in the form of carbohydrates, and molecular oxygen. Molecular oxygen is derived from the light-induced oxidation of substrate water molecules. Photosynthetic oxygen production takes place within the Photosystem II (PSII) complex, a collection of proteins, pigments, and inorganic metal ions, which function together to oxidize water and release molecular oxygen to the atmosphere. One-electron transfer reactions in the chlorophyll-containing photosystem II reaction center are coupled to the four-electron oxidation of water in the oxygen-evolving complex (OEC). The OEC contains a tetramanganese-calcium cluster (Mn cluster) (Fig. 1A), and chloride plays an important role in facilitating catalysis. Four successive photooxidations are required for the splitting of two water molecules to produce molecular