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Structural Dynamics of the Oxygen-Evolving Complex of Photosystem II in Water-Splitting Action
journal contribution
posted on 2018-04-12, 00:00 authored by Andrew
J. Wilson, Prashant K. JainOxygenic photosynthesis in nature
occurs via water splitting catalyzed
by the oxygen-evolving complex (OEC) of photosystem II. To split water,
the OEC cycles through a sequence of oxidation states (Si, i = 0–4), the structural
mechanism of which is not fully understood under physiological conditions.
We monitored the OEC in visible-light-driven water-splitting action
by using in situ, aqueous-environment surface-enhanced
Raman scattering (SERS). In the unexplored low-frequency region of
SERS, we found dynamic vibrational signatures of water binding and
splitting. Specific snapshots in the dynamic SERS correspond to intermediate
states in the catalytic cycle, as determined by density functional
theory and isotopologue comparisons. We assign the previously ambiguous
protonation configuration of the S0–S3 states and propose a structural mechanism of the OEC’s catalytic
cycle. The findings address unresolved questions about photosynthetic
water splitting and introduce spatially resolved, low-frequency SERS
as a chemically sensitive tool for interrogating homogeneous catalysis in operando.
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OEC cyclessplit watervibrational signaturesisotopologue comparisonsprotonation configurationWater-Splitting Action Oxygenic photosynthesisSERSaqueous-environment surface-enhanced Ramanoxidation statesmechanismSpecific snapshotswater bindingPhotosystem IIS iOxygen-Evolving ComplexStructural Dynamicsvisible-light-driven water-splitting actionphotosystem IIfindings addressphotosynthetic water splittingwater splitting
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