期刊
ACTA PHYSICO-CHIMICA SINICA
卷 26, 期 7, 页码 2021-2030出版社
PEKING UNIV PRESS
DOI: 10.3866/PKU.WHXB20100730
关键词
Ultrafast spectroscopy; Photosynthesis; Light-harvesting complex 2; Excitation energy transfer
资金
- National Key Basic Research Program of China (973) [2009CB220008]
- National Natural Science Foundation of China [20711140133, 20703067]
- Renmin University of China [10XNI007]
Purple photosynthetic bacterium Thermochromatium (Tch.) tepidum is a moderate thermophile growing in an optimal temperature range of 48-50 degrees C. Its light-harvesting complex 2 (LH2) possesses heterogeneous compositions of apoprotein and carotenoid (Car), but the high. resolution crystallographic structure remains unknown. We have attempted an ultrafast time. resolved spectroscopic study of the isolated LH2 complex from Tch. tepidum. The spectral dynamics and population kinetics of n-dodecyl-beta-D-moltoside (DDM) and lauryldimethylamine oxide (LDAO) preparations of LH2 reveal efficient S-2-state mediated Car-to-Car and Car-to-bacteriochlorophyll (BChl) singlet excitation energy transfer (EET) occurring in a time scale of similar to 100 fs, as well as the Q(y)-state mediated B800-to-B850 singlet EET for the DDM preparation proceeding with a time constant of similar to 1.2 ps. These ultrafast EET processes suggest that the Cars with 11 and 12 conjugated C=C double bonds (N-C=C) coexist in the LH2 complex, and that the B800-B850 mutual orientation in LH2 differs considerably from those in the LH2s from some of the previously investigated bacterial species. In addition, anhydrorhodovibrin (N-C=C=12) as a minor Car composition is found to act as an efficient trap of excitation energy, which is considered to be an important photoprotection mechanism. Furthermore, based on the results of ultrafast Car band shift in response to BChl excitation, we propose that, compared to other Car compositions, (OH-) spirilloxanthin (N-C=C=13) locates in closer proximity to BChl. Our results may facilitate to understand the light. harvesting and the photoprotection mechanisms of Tch. tepidum living under harsh natural conditions.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据