Proton Translocation via Tautomerization of Asn298 During the S₂-S₃ State Transition in the Oxygen-Evolving Complex of Photosystem II.

ABSTRACT: In biological water oxidation, a redox-active tyrosine residue (D1-Tyr161 or Y_Z) mediates electron transfer between the Mn₄CaO₅ cluster of the oxygen-evolving complex and the charge-separation site of photosystem II (PSII), driving the cluster through progressively higher oxidation states S _i ( i = 0-4). In contrast to lower S-states (S₀, S₁), in higher S-states (S₂, S₃) of the Mn₄CaO₅ cluster, Y_Z cannot be oxidized at cryogenic temperatures due to the accumulation of positive charge in the S₁ → S₂ transition. However, oxidation of Y_Z by illumination of S₂ at 77-190 K followed by rapid freezing and charge recombination between

SUBMITTER: Chrysina M 

PROVIDER: S-EPMC6727346 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature