Initial electron donor and acceptor in isolated Photosystem II reaction centers identified with femtosecond mid-IR spectroscopy
Initial electron donor and acceptor in isolated Photosystem II reaction centers identified with femtosecond mid-IR spectroscopy
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DOI：
10.1073/pnas.0503483102
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发表时间：
2005-09-13
影响因子：
11.1
通讯作者：
van Grondelle, R
中科院分区：
文献类型：
--
作者：
Groot, ML;Pawlowicz, NP;van Grondelle, R
尽管植物光系统11反应中心（RC）和紫色细菌对应物之间存在明显的相似性，但我们在这项工作中表明，两个光合RC的电荷分离机制非常不同。通过使用飞秒可见光泵浦中红外探测光谱在叶绿素酯和酮模式的区域，在1,775和1,585 cm（-1）之间，150 fs的时间分辨率，我们表明，脱镁叶绿素的还原发生在0.6至0.8 ps的时间尺度上，而P+，水氧化的前体状态，形成后约6 ps。因此，我们得出结论，在光系统11 RC的主要电荷分离发生在“辅助叶绿素”ChI（D1）和脱镁叶绿素之间的所谓的活性分支。
Despite the apparent similarity between the plant Photosystem 11 reaction center (RC) and its purple bacterial counterpart, we show in this work that the mechanism of charge separation is very different for the two photosynthetic RCs. By using femtosecond visible-pump-mid-infrared probe spectroscopy in the region of the chlorophyll ester and keto modes, between 1,775 and 1,585 cm(-1), with 150-fs time resolution, we show that the reduction of pheophytin occurs on a 0.6- to 0.8-ps time scale, whereas P+, the precursor state for water oxidation, is formed after approximate to 6 ps. We conclude therefore that in the Photosystem 11 RC the primary charge separation occurs between the "accessory chlorophyll" ChI(D1) and the pheophytin on the so-called active branch.