A big step toward the realization of artificial photosynthesis: Success in capturing the moment when the "warped chair" type catalyst responsible for photosynthesis takes in water molecules at the nanosecond level.

Key Points

In photosynthesis, a membrane protein complex called photosystem II uses light energy to produce molecular oxygen from water molecules.

Using a femtosecond X-ray free electron laser, we succeeded in capturing a series of movements of the "warped chair" type catalyst of photosystem II from the uptake of water molecules to the completion of the preparation for oxygen molecule formation.

This research result provides important guidelines not only for elucidating the mechanism of photosynthesis to extract hydrogen ions and electrons from water molecules, but also for designing artificial photosynthetic catalysts for water splitting with light.


Photosynthesis begins with the reaction in which photosystem II uses light energy to extract electrons and hydrogen ions from water molecules to form oxygen.

After the reaction is initiated by irradiating the crystals of Photosystem II with visible light, the three-dimensional structure of the "warped chair" catalyst of Photosystem II in the series of movements until it is ready to take up water molecules and produce oxygen molecules was studied using femtosecond X-rays at the X-ray free electron laser facility SACLA.

The three-dimensional structure of the movement of the "warped chair"-type catalyst of Photosystem II from the time scale of nanoseconds (one nanosecond is one billionth of a second) to milliseconds until the catalyst takes in water molecules and completes the preparation of oxygen molecules was successfully captured. As a result, it was found that proteins, water molecules, and light-harvesting pigments work concertedly like an orchestra inside photosystem II to facilitate the movement of water and the discharge of hydrogen ions.

The mechanism for forming oxygen molecules revealed in this research is expected to provide important insights into the development of artificial photosynthesis, a technology that uses light energy to extract electrons and hydrogen ions from water to produce useful chemical substances.

Publication details

Oxygen-evolving photosystem II structures during S1-S2 -S3 transitions

Hongjie Li, Yoshiki Nakajima, Eriko Nango, Shigeki Owada, Daichi Yamada, Kana Hashimoto, Fangjia Luo, Rie Tanaka, Fusamichi Akita, Koji Kato, Jungmin Kang, Yasunori Saitoh, Shunpei Kishi, Huaxin Yu, Naoki Matsubara, Hajime Fujii, Michihiro Sugahara, Mamoru Suzuki, Tetsuya Masuda, Tetsunari Kimura, Tran Nguyen Thao, Shinichiro Yonekura, Long-Jiang Yu, Takehiko Tosha, Kensuke Tono, Yasumasa Joti, Takaki Hatsui, Makina Yabashi, Minoru Kubo, So Iwata, Hiroshi Isobe, Kizashi Yamaguchi, Michihiro Suga*, Jian-Ren Shen*





Prof. Eriko NANGO
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