"NH3 Binding to the S2 State of the O2" by Mikhail Askerka, David J. Vinyard et al.

Faculty Publications

Title

NH₃ Binding to the S₂ State of the O₂-Evolving Complex of Photosystem II: Analogue to H₂O Binding during the S₂ → S₃ Transition

Authors

Mikhail Askerka, Yale University
David J. Vinyard, Yale University
Gary W. Brudvig, Yale University
Victor S. Batista, Yale University

Document Type

Article

Publication Date

9-29-2015

Abstract

© 2015 American Chemical Society. Ammonia binds directly to the oxygen-evolving complex of photosystem II (PSII) upon formation of the S2 intermediate, as evidenced by electron paramagnetic resonance spectroscopy. We explore the binding mode by using quantum mechanics/molecular mechanics methods and simulations of extended X-ray absorption fine structure spectra. We find that NH3 binds as an additional terminal ligand to the dangling Mn4, instead of exchanging with terminal water. Because water and ammonia are electronic and structural analogues, these findings suggest that water binds analogously during the S2 → S3 transition, leading to rearrangement of ligands in a carrousel around Mn4.

Publication Source (Journal or Book title)

Biochemistry

First Page

5783

Last Page

5786

Recommended Citation

Askerka, M., Vinyard, D., Brudvig, G., & Batista, V. (2015). NH₃ Binding to the S₂ State of the O₂-Evolving Complex of Photosystem II: Analogue to H₂O Binding during the S₂ → S₃ Transition. Biochemistry, 54 (38), 5783-5786. https://doi.org/10.1021/acs.biochem.5b00974

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