Reply to Wang Et Al.: Clear Evidence of Binding of Ox to the Oxygen-Evolving Complex of Photosystem II is Best Observed in the Omit Map.

Wang their own analysis of our crystallographic data (2) and our, and similar previous (3 – 5), results that a newly inserted water (Ox) in the catalytic center of photosystem II (PSII) can be uniquely identified in the room temperature crystal structures taken at various time points during the S 2 -to-S 3 transition of the water oxidation reaction in PSII. They suggest that the results can be explained by the movement of the existing ligand, O5, without incorporating a new water (Ox). The following four points describe why their claim is not valid.