Oxygenic photoreactivity in photosystem II studied by rotating ring disk electrochemistry

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Title: Oxygenic photoreactivity in photosystem II studied by rotating ring disk electrochemistry
Author(s): Kornienko, N
Zhang, JZ
Sokol, K
Lamaison, S
Fantuzzi, A
Van Grondelle, R
Rutherford, AW
Reisner, E
Item Type: Journal Article
Abstract: 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 superoxide 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.
Publication Date: 6-Sep-2018
Date of Acceptance: 6-Sep-2018
URI: http://hdl.handle.net/10044/1/64477
DOI: https://dx.doi.org/10.1021/jacs.8b08784
ISSN: 1520-5126
Publisher: American Chemical Society
Journal / Book Title: Journal of the American Chemical Society
Sponsor/Funder: Biotechnology and Biological Sciences Research Council (BBSRC)
Biotechnology and Biological Sciences Research Council (BBSRC)
Funder's Grant Number: BB/K002627/1
Copyright Statement: © 2018 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
Keywords: 03 Chemical Sciences
General Chemistry
Publication Status: Published online
Conference Place: United States
Online Publication Date: 2018-09-06
Appears in Collections:Faculty of Natural Sciences

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