Assessment of the manganese cluster's oxidation state via photoactivation of photosystem II microcrystals.

ABSTRACT: Knowledge of the manganese oxidation states of the oxygen-evolving Mn₄CaO₅ cluster in photosystem II (PSII) is crucial toward understanding the mechanism of biological water oxidation. There is a 4 decade long debate on this topic that historically originates from the observation of a multiline electron paramagnetic resonance (EPR) signal with effective total spin of S = 1/2 in the singly oxidized S₂ state of this cluster. This signal implies an overall oxidation state of either Mn(III)₃Mn(IV) or Mn(III)Mn(IV)₃ for the S₂ state. These 2 competing assignments are commonly known as "low oxidation (LO)" and "high oxidation (HO)" models of the Mn₄CaO₅ cluster. Recent advanced EPR and Mn K-edge X-ray spectro

SUBMITTER: Cheah MH 

PROVIDER: S-EPMC6955365 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature