Oxygenic Photoreactivity in Photosystem II Studied by Rotating Ring Disk Electrochemistry.
Oxygenic Photoreactivity in Photosystem II Studied by Rotating Ring Disk Electrochemistry.
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DOI：
10.1021/jacs.8b08784
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发表时间：
2018-12-26
影响因子：
15
通讯作者：
Reisner E
中科院分区：
文献类型：
--
作者：
Kornienko N;Zhang JZ;Sokol KP;Lamaison S;Fantuzzi A;van Grondelle R;Rutherford AW;Reisner E
蛋白质膜光电化学以前被用来监测光系统II的活性，但从三电极装置获得的机制信息仍然有限。在这里，我们介绍了四电极旋转环盘电极技术，用于实时定量酶-电极界面上的光驱动反应动力学和机理路径。这一设置使我们能够研究光系统II中的光化学H2O氧化，并深入了解产生活性氧物种的途径。结果表明，光系统II通过两个主要途径与O2反应，这两个途径都涉及一个超氧化物中间体来产生H_2O_2。第一种途径包括已建立的叶绿素三重态介导的单线态氧的形成，随后在电极表面将其还原为超氧化物。第二条途径是酶/电极界面所特有的：暴露的天线叶绿素足够靠近电极，以便快速注入电子形成高度还原的叶绿素阴离子，该阴离子与溶液中的O2反应生成O2·-。在我们的条件下，不完全的H2O氧化不会显著地促进活性氧的形成。旋转环盘电极技术可以用电化学法研究光系统II的化学反应性，并为未来的研究开辟了几条途径。
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 an 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.
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DOI：
10.1002/anie.201805027
发表时间：
2018-08-13
期刊：
Angewandte Chemie (International ed. in English)
影响因子：
--
作者：
Nam DH;Zhang JZ;Andrei V;Kornienko N;Heidary N;Wagner A;Nakanishi K;Sokol KP;Slater B;Zebger I;Hofmann S;Fontecilla-Camps JC;Park CB;Reisner E
通讯作者：
Reisner E
影响因子：
2.9
作者：
Frankel, Laurie K.;Sallans, Larry;Bricker, Terry M.
通讯作者：
Bricker, Terry M.
影响因子：
15
作者：
Kato, Masaru;Cardona, Tanai;Reisner, Erwin
通讯作者：
Reisner, Erwin
影响因子：
3.5
作者：
Cleland, RE;Grace, SC
通讯作者：
Grace, SC
影响因子：
3.5
作者：
Kozuleva, Marina A.;Petrova, Anastasia A.;Ivanov, Boris N.
通讯作者：
Ivanov, Boris N.