Cryogenic Single-Molecule Spectroscopy of the Primary Electron Acceptor in Photosynthetic Reaction Center
Cryogenic Single-Molecule Spectroscopy of the Primary Electron Acceptor in Photosynthetic Reaction Center
复制标题
光合反应中心初级电子受体的低温单分子光谱研究
DOI：
10.1021/acs.jpclett.0c00891
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发表时间：
2020
影响因子：
4.4
通讯作者：
and M. Matsushita
中科院分区：
文献类型：
--
作者：
T. Kondo;R. Mutoh;H. Tabe;G. Kurisu;H. Oh-oka;S. Fujiyoshi;and M. Matsushita
光合作用反应中心(RC)将光能转化为电化学能。幽门螺杆菌RC是一种原始的同源二聚体RC，含有58个细菌叶绿素和2个叶绿素。叶绿素是主要的电子受体(Chla-A0)，负责光捕获和电荷分离。Chla-A0的单分子光谱可以用来研究RC光化学功能的异质性，但荧光量子产率低(0.1%)使研究变得困难。在这里，我们展示了在6K下单个CHLA-A0在单个HRCS中的荧光激发光谱，与室温下相比，ChLA-A0的荧光量子产率和吸收截面分别增加了2倍和4倍。在单一的HRCS中，两个Chla-A0在荧光激发光谱中被确定为两个不同的峰，表现出不同的激发偏振关系。光漂白引起的光谱变化表明了HRC中各亚基之间的能量转移。
The photosynthetic reaction center (RC) converts light energy into electrochemical energy. The RC of heliobacteria (hRC) is a primitive homodimeric RC containing 58 bacteriochlorophylls and 2 chlorophyllas. The chlorophyll serves as the primary electron acceptor (Chla-A0) responsible for light harvesting and charge separation. The single-molecule spectroscopy of Chla-A0can be used to investigate heterogeneities of the RC photochemical function, though the low fluorescence quantum yield (0.1%) makes it difficult. Here, we show the fluorescence excitation spectroscopy of individual Chla-A0s in single hRCs at 6 K. The fluorescence quantum yield and absorption cross section of Chla-A0increase 2- and 4-fold, respectively, compared to those at room temperature. The two Chla-A0s in single hRCs are identified as two distinct peaks in the fluorescence excitation spectrum, exhibiting different excitation polarization dependences. The spectral changes caused by photobleaching indicate the energy transfer across subunits in the hRC.