Figure 7.

Catalytic cycle of water splitting suggested by DFT QM/MM models of the OEC of PSII (Sproviero et al. 2007d). Dashed arrows in brown indicate transformations leading to the following S-state in the cycle. Changes caused by an S-state transition are highlighted in red. The blue circles highlight substrate water molecules (also shown in blue). Coordination bonds elongated by Jahn-Teller distorsions are marked in green. The oxidation states of Mn ions are indicated as Roman superscripts, while the orientation of the metal cluster corresponds to Fig. 2, where Mn(1), Mn(2), Mn(3) and Mn(4) are indicated.