Exploring the Deprotonation Process during Incorporation of a Ligand Water Molecule at the Dangling Mn Site in Photosystem II.

ABSTRACT: The Mn₄CaO₅ cluster, featuring four ligand water molecules (W1 to W4), serves as the water-splitting site in photosystem II (PSII). X-ray free electron laser (XFEL) structures exhibit an additional oxygen site (O6) adjacent to the O5 site in the fourth lowest oxidation state, S₃, forming Mn₄CaO₆. Here, we investigate the mechanism of the second water ligand molecule at the dangling Mn (W2) as a potential incorporating species, using a quantum mechanical/molecular mechanical (QM/MM) approach. Previous QM/MM calculations demonstrated that W1 releases two protons through a low-barrier H-bond toward D1-Asp61 and subsequently releases an electron during the S₂ to S₃ transition, resulting in O^•- at W1 and pro

SUBMITTER: Saito K 

PROVIDER: S-EPMC11104351 | biostudies-literature | 2024 May

REPOSITORIES: biostudies-literature