Fig. 4: Mn4CaO5 structures including the second sphere ligand residues (D1-Asp61 and CP43-Arg357) in S1.
From: pKa of the ligand water molecules in the oxygen-evolving Mn4CaO5 cluster in photosystem II
Dotted lines indicate ligations of the ligand water molecules to metal ions. a Quantum-chemically optimized structure in the absence of the PSII protein environment. W1 is stabilized as OH− in the presence of protonated D1-Asp61, as the release of the proton occurs from H2O at W1 to ionized D1-Asp61. b QM/MM-optimized Mn4CaO5 structure in the PSII protein environment.
