AI Article Synopsis
- The oxygen-evolving complex (OEC) in photosystem II contains a mix of manganese and calcium ions, along with bound chloride ions.
- Research indicates that increasing sodium concentration enhances the oxygen-evolution rate of spinach photosystem II, especially at higher pH levels.
- A newly identified sodium-specific binding site near the OEC may become accessible after changes in the D1-H337 amino acid, as supported by advanced microscopy and simulation techniques.
Article Abstract
The oxygen-evolving complex (OEC) of photosystem II (PSII) is an oxomanganese cluster composed of four redox-active Mn ions and one redox-inactive Ca ion, with two nearby bound Cl ions. Sodium is a common counterion of both chloride and hydroxide anions, and a sodium-specific binding site has not been identified near the OEC. Here, we find that the oxygen-evolution activity of spinach PSII increases with Na concentration, particularly at high pH. A Na-specific binding site next to the OEC, becomes available after deprotonation of the D1-H337 amino acid residue, is suggested by the analysis of two recently published PSII cryo-electron microscopy maps in combination with quantum mechanical calculations and multiconformation continuum electrostatics simulations.
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| http://dx.doi.org/10.1021/acs.biochem.0c00303 | DOI Listing |
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