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3-dimensional configuration of the electron transfer chain in photosynthesis studied by pulsed EPR

脉冲 EPR 研究光合作用中电子传递链的 3 维构型

基本信息

批准号：
13640412
负责人：
KAWAMORI Asako
金额：
$ 2.24万
依托单位：
Kwansei Gakuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640412/
关键词：
Photosystem II ELDOR Distance Vector 3 Spin System Dipolar Interaction Chlorophyll Quinone Tyrosine 光合成電子伝達 3スピン系ELDOR マンガン銅 P680

项目摘要

a) ELDOR of 3-spin systems to investigate the configuration of electron transfer componentsSo far we have obtained the distances between Tyrosines Z(Y_Z) and D(Y_D), and Q_A and Y_D in spinach photosystem II. To investigate the unknown distance between Q_A and Y_Z, pulsed ELDOR was applied to a 3-spin system Y_D^・-Y_Z^・-Q_A^-. As all the 3-spin systems could not be always trapped, simulation was carried out for assumed ratios of the three spin system and other pair of two spin systems to fit the observed time profile. The best fit distance for Q_A-Y_Z was 34 A. To confirm, ELDOR of Q_A^<->-Y_Z^・ was observed in a Y_D-less mutant of Chlamydomonas reinhardtii. A graphical method was proposed to get positions of all the electron transfer components.b) Determination of the functional site.When electron transfer is inhibited, a chlorophyll near by the reaction center gives an electron to P680^+ instead of the second donor Y_Z and the oxidized chlorophyll was named Chl_Z^・. However, which chlorophyll in D1 or D2 proteins act functional, has not yet determined. ELDOR for Y_D-Chl_Z provided that the distance between these radicals was 29.5 A. ELDOR of Y_D^・-Chl_Z^・-Q_A^- system and Y_Z^・-Chl_Z^・. In the Y_D-less mutant revealed the accessory chlorophyll on the D2 protein is the functional site.c) Change in the spin configuration on four manganese site on oxidation,The distances of the Mn-cluster in the S_0 and S_2 states, respectively, from Y_D have been shown to be 7 A different. Assuming the simple dipolar interaction the spin center of the Mn-cluster approached from S_0 to S_2 state to the Y_D site. This value seems to be too large based on the recent X-ray analysis. Taking account of spin projections on each Mn-ion, detailed simulations are being undertaken in cooperation with Bittl in Free University Berlin.

a）用ELDOR方法研究了菠菜光系统II中电子转移组分的构型，得到了酪氨酸分子Z（Y_Z）和D（Y_D）之间的距离以及酪氨酸分子Q_A和Y_D之间的距离。为了研究Q_A和Y_Z之间的未知距离，我们将脉冲ELDOR应用于三自旋系统Y_D^·-Y_Z^·-Q_A^-。由于并非所有的三自旋系统都能被捕获，因此对三自旋系统和另一对两自旋系统的假设比例进行了模拟，以拟合观测到的时间剖面。Q_A-Y_Z的最佳拟合距离为34 A。为了证实这一点，在莱茵<->衣藻Y_D缺失突变体中观察到Q_A^ -Y_Z^·的ELDOR。B）功能位的确定：当电子传递受到抑制时，靠近反应中心的叶绿素将电子传递给P680^+而不是第二供体Y_Z，氧化叶绿素被命名为Chl_Z^·。然而，D1或D2蛋白中的叶绿素起作用，尚未确定。Y_D-Chl_Z的ELDOR公式中，两个自由基之间的距离为29.5A。E_D^·-Chl_Z^·-Q_A^-系统和Y_Z^·-Chl_Z^·的ELDOR。在Y_D缺失突变体中，D_2蛋白上的辅助叶绿素是功能位点。c）四个锰位点的自旋构型在氧化过程中发生了变化，S_0和S_2态的Mn簇离Y_D的距离相差7埃。在简单偶极相互作用下，Mn团簇的自旋中心从S_0态向S_2态靠近Y_D位。根据最近的X射线分析，该值似乎太大。考虑到每个Mn离子的自旋投影，正在与柏林自由大学的Bittl合作进行详细的模拟。