Dynamics of Energy and Electron Transfer in the FMO-Reaction Center Core Complex from the Phototrophic Green Sulfur Bacterium Chlorobaculum tepidum

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• 作者：Guannan He ; Dariusz M. Niedzwiedzki ; Gregory S. Orf ; Hao Zhang ; Robert E. Blankenship
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：119
• 期：26
• 页码：8321-8329
• 全文大小：482K
• ISSN：1520-5207

文摘

The reaction center core (RCC) complex and the RCC with associated Fenna鈥揗atthews鈥揙lson protein (FMO-RCC) complex from the green sulfur bacterium Chlorobaculum tepidum were studied comparatively by steady-state and time-resolved fluorescence (TRF) and femtosecond time-resolved transient absorption (TA) spectroscopies. The energy transfer efficiency from the FMO to the RCC complex was calculated to be 鈭?0% based on the steady-state fluorescence. TRF showed that most of the FMO complexes (66%), regardless of the fact that they were physically attached to the RCC, were not able to transfer excitation energy to the reaction center. The TA spectra of the RCC complex showed a 30鈥?8 ps lifetime component regardless of the excitation wavelengths, which is attributed to charge separation. Excitonic equilibration was shown in TA spectra of the RCC complex when excited into the BChl a Q_x band at 590 nm and the Chl a Q_y band at 670 nm, while excitation at 840 nm directly populated the low-energy excited state and equilibration within the excitonic BChl a manifold was not observed. The TA spectra for the FMO-RCC complex excited into the BChl a Q_x band could be interpreted by a combination of the excited FMO protein and RCC complex. The FMO-RCC complex showed an additional fast kinetic component compared with the FMO protein and the RCC complex, which may be due to FMO-to-RCC energy transfer.