Kern Jan, Tran Rosalie, Alonso-Mori Roberto, Koroidov Sergey, Echols Nathaniel, Hattne Johan, Ibrahim Mohamed, Gul Sheraz, Laksmono Hartawan, Sierra Raymond G, Gildea Richard J, Han Guangye, Hellmich Julia, Lassalle-Kaiser Benedikt, Chatterjee Ruchira, Brewster Aaron S, Stan Claudiu A, Glöckner Carina, Lampe Alyssa, DiFiore Dörte, Milathianaki Despina, Fry Alan R, Seibert M Marvin, Koglin Jason E, Gallo Erik, Uhlig Jens, Sokaras Dimosthenis, Weng Tsu-Chien, Zwart Petrus H, Skinner David E, Bogan Michael J, Messerschmidt Marc, Glatzel Pieter, Williams Garth J, Boutet Sébastien, Adams Paul D, Zouni Athina, Messinger Johannes, Sauter Nicholas K, Bergmann Uwe, Yano Junko, Yachandra Vittal K
1] Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Nat Commun. 2014 Jul 9;5:4371. doi: 10.1038/ncomms5371.
The dioxygen we breathe is formed by light-induced oxidation of water in photosystem II. O2 formation takes place at a catalytic manganese cluster within milliseconds after the photosystem II reaction centre is excited by three single-turnover flashes. Here we present combined X-ray emission spectra and diffraction data of 2-flash (2F) and 3-flash (3F) photosystem II samples, and of a transient 3F' state (250 μs after the third flash), collected under functional conditions using an X-ray free electron laser. The spectra show that the initial O-O bond formation, coupled to Mn reduction, does not yet occur within 250 μs after the third flash. Diffraction data of all states studied exhibit an anomalous scattering signal from Mn but show no significant structural changes at the present resolution of 4.5 Å. This study represents the initial frames in a molecular movie of the structural changes during the catalytic reaction in photosystem II.
我们呼吸的氧气是由光系统II中光诱导的水氧化形成的。在光系统II反应中心被三个单周转闪光激发后的几毫秒内，氧气在催化锰簇处形成。在这里，我们展示了在功能条件下使用X射线自由电子激光收集的2闪光（2F）和3闪光（3F）光系统II样品以及瞬态3F'状态（第三次闪光后250微秒）的组合X射线发射光谱和衍射数据。光谱表明，在第三次闪光后250微秒内，与锰还原相关的初始O-O键形成尚未发生。所研究的所有状态的衍射数据都显示出锰的反常散射信号，但在目前4.5埃的分辨率下没有显示出明显的结构变化。这项研究代表了光系统II催化反应过程中结构变化分子电影的初始画面。
