Oxygenic Photoreactivity in Photosystem II Studied by Rotating Ring Disk Electrochemistry.
van Grondelle, Rienk
Journal of the American Chemical Society
American Chemical Society (ACS)
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Kornienko, N., Zhang, J., Sokol, K., Lamaison, S., Fantuzzi, A., van Grondelle, R., Rutherford, A. W., & et al. (2018). Oxygenic Photoreactivity in Photosystem II Studied by Rotating Ring Disk Electrochemistry.. Journal of the American Chemical Society, 140 (51), 17923-17931. https://doi.org/10.1021/jacs.8b08784
Protein film photoelectrochemistry has previously been used to monitor the activity of Photosystem II, the water-plastoquinone photooxidoreductase, but the mechanistic information attainable from a three-electrode setup has remained limited. Here we introduce the four-electrode rotating ring disk electrode technique for quantifying light-driven reaction kinetics and mechanistic pathways in real time at the enzyme-electrode interface. This setup allows us to study photochemical H2O oxidation in Photosystem II and to gain in-depth understanding of pathways that generate reactive oxygen species. The results show that Photosystem II reacts with O2 through two main pathways that both involve a super-oxide intermediate to produce H2O2. The first pathway involves the established chlorophyll triplet-mediated formation of singlet oxygen, which is followed by its reduction to superoxide at the electrode surface. The second pathway is specific for the enzyme/electrode interface: an exposed antenna chlorophyll is sufficiently close to the electrode for rapid injection of an electron to form a highly reducing chlorophyll anion, which reacts with O2 in solution to produce O2•–. Incomplete H2O oxidation does not significantly contribute to reactive oxygen formation in our conditions. The rotating ring disk electrode technique allows the chemical reactivity of Photosystem II to be studied electrochemically and opens several avenues for future investigation.
Is supplemented by: https://doi.org/10.17863/CAM.27714
Royal Society Newton International Fellowship, ERC Consollidator Grant, BBSRC, EPSRC, French Corps of Bridges, Waters & Forests, VU University Amsterdam, ERC Advanced Investigator grant, EU FP7 project, Academy Professor grant from the Netherlands Royal Academy of Sciences
ECH2020 EUROPEAN RESEARCH COUNCIL (ERC) (682833)
External DOI: https://doi.org/10.1021/jacs.8b08784
This record's URL: https://www.repository.cam.ac.uk/handle/1810/285354
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/