The exchange of the fast substrate water in the S₂ state of photosystem II is limited by diffusion of bulk water through channels - implications for the water oxidation mechanism.

ABSTRACT: The molecular oxygen we breathe is produced from water-derived oxygen species bound to the Mn₄CaO₅ cluster in photosystem II (PSII). Present research points to the central oxo-bridge O5 as the 'slow exchanging substrate water (W_s)', while, in the S₂ state, the terminal water ligands W2 and W3 are both discussed as the 'fast exchanging substrate water (W_f)'. A critical point for the assignment of W_f is whether or not its exchange with bulk water is limited by barriers in the channels leading to the Mn₄CaO₅ cluster. In this study, we measured the rates of H₂ ¹⁶O/H₂ ¹⁸O substrate water exchange in the S₂ and S₃ states of PSII core complexes

SUBMITTER: de Lichtenberg C 

PROVIDER: S-EPMC8494045 | biostudies-literature | 2021 Oct

REPOSITORIES: biostudies-literature