Ultrafast infrared observation of exciton equilibration from oriented single crystals of photosystem II.
Ultrafast infrared observation of exciton equilibration from oriented single crystals of photosystem II.
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DOI：
10.1038/ncomms13977
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发表时间：
2016-12-23
影响因子：
16.6
通讯作者：
van Thor JJ
中科院分区：
文献类型：
--
作者：
Kaucikas M;Maghlaoui K;Barber J;Renger T;van Thor JJ
在产氧光合作用中，两个光系统串联工作。它们中的每一个都包含一个被捕光天线包围的反应中心，捕光天线吸收光并将激发能量转移到驱动电子转移反应的反应中心。在这里，我们报告了对光系统II核心的两种对比光捕获模型（称为陷阱限制模型和转移到陷阱限制模型）的关键测试。利用偏振可见光激发细长聚球藻（Synechococcus elongatus）光系统II核心复合物的定向单晶，并利用红外偏振光探测其瞬态吸收。由光选择产生的二向色振幅保持在60 ps的时间尺度上，该时间尺度对应于占主导地位的能量转移过程，为整个捕光过程的转移到陷阱的限制提供了令人信服的证据。这一发现对激发态的淬灭具有功能意义，使植物能够在强光下生存。有两种常见的模型光合光收获的光系统II核心。在这里，作者使用结构敏感，时间分辨红外多色性的光系统II核心复合物的单晶探测激子平衡，区分模型。
In oxygenic photosynthesis, two photosystems work in series. Each of them contains a reaction centre that is surrounded by light-harvesting antennae, which absorb the light and transfer the excitation energy to the reaction centre where electron transfer reactions are driven. Here we report a critical test for two contrasting models of light harvesting by photosystem II cores, known as the trap-limited and the transfer-to-the trap-limited model. Oriented single crystals of photosystem II core complexes of Synechococcus elongatus are excited by polarized visible light and the transient absorption is probed with polarized light in the infrared. The dichroic amplitudes resulting from photoselection are maintained on the 60 ps timescale that corresponds to the dominant energy transfer process providing compelling evidence for the transfer-to-the-trap limitation of the overall light-harvesting process. This finding has functional implications for the quenching of excited states allowing plants to survive under high light intensities. There are two common models of photosynthetic light harvesting by photosystem II cores. Here, the authors use structurally sensitive, time resolved infrared pleochroism of single crystals of photosystem II core complexes to probe the exciton equilibration that discriminates between the models.