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Updated: Oct 12, 2025

Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts
Published on: August 7, 2018
Chloride facilitates Mn(III) formation during photoassembly of the Photosystem II oxygen-evolving complex
Brandon P Russell1, David J Vinyard2
1Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
Abstract:
The Mn4Ca oxygen-evolving complex (OEC) in Photosystem II (PSII) is assembled in situ from free Mn2+, Ca2+, and water. In an early light-driven step, Mn2+ in a protein high-affinity site is oxidized to Mn3+. Using dual-mode electron paramagnetic resonance spectroscopy, we observed that Mn3+ accumulation increases as chloride concentration increases in spinach PSII membranes depleted of all extrinsic subunits. At physiologically relevant pH values, this effect requires the presence of calcium. When combined with pH studies, we conclude that the first Mn2+ oxidation event in OEC assembly requires a deprotonation that is facilitated by chloride.
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