Alternative Excitonic Structure in the Baseplate (BChl a鈥揅smA Complex) of the Chlorosome from Chlorobaculum tepidum

详细信息    查看全文

• 作者：Adam Kell ; Jinhai Chen ; Mahboobe Jassas ; Joseph Kuo-Hsiang Tang ; Ryszard Jankowiak
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：July 16, 2015
• 年：2015
• 卷：6
• 期：14
• 页码：2702-2707
• 全文大小：311K
• ISSN：1948-7185

文摘

In the photosynthetic green sulfur bacterium Chlorobaculum tepidum, the baseplate mediates excitation energy transfer from the light-harvesting chlorosome to the Fenna鈥揗atthews鈥揙lson (FMO) complex and subsequently toward the reaction center (RC). Literature data suggest that the baseplate is a 2D lattice of BChl a鈥揅smA dimers. However, recently, it has been proposed, using 2D electronic spectroscopy (2DES) at 77 K, that at least four excitonically coupled BChl a are in close contact within the baseplate structure [trib-group>Dost谩l, J.trib-group>; et al., te>J. Phys. Chem. Lett.te> 2014, 5, 1743]. This finding is tested via hole burning (HB) spectroscopy (5 K). Our results indicate that the four excitonic states identified by 2DES likely correspond to contamination of the baseplate with the FMO antenna and possibly the RC. In contrast, HB reveals a different excitonic structure of the baseplate chromophores, where excitation is transferred to a localized trap state near 818 nm via exciton hopping, which leads to emission near 826 nm.