Mechanism of energy transfer from carotenoids to Bacteriochlorophyll:: Light-harvesting by carotenoids having different extents of π-electron conjugation incorporated into the B850 antenna complex from the carotenoidless bacterium Rhodobacter sphaeroides R-26.1
Mechanism of energy transfer from carotenoids to Bacteriochlorophyll:: Light-harvesting by carotenoids having different extents of π-electron conjugation incorporated into the B850 antenna complex from the carotenoidless bacterium Rhodobacter sphaeroides R-26.1
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DOI：
10.1021/jp980911j
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发表时间：
1998-10-15
影响因子：
3.3
通讯作者：
Frank, HA
中科院分区：
文献类型：
--
作者：
Desamero, RZB;Chynwat, V;Frank, HA
类球红细菌R-26.1的B850捕光复合物中引入了类球红细菌和一系列具有7 - 13个碳-碳双键的类球红细菌类似物。利用稳态吸收光谱、荧光光谱、荧光激发光谱、共振拉曼光谱和时间分辨吸收光谱研究了B850复合物中类胡萝卜素的结构和光谱性质以及类胡萝卜素与细菌叶绿素（BChl）之间的能量传递动力学。本研究中使用的类球蛋白类似物为5 '，6'-二氢-7 '，8'-二脱氢类球蛋白、7 '，8'-二脱氢类球蛋白和1 '，2'-二氢-3 '，4'，7 '，8'-四脱氢类球蛋白。这些数据与已经发表的3，4，7，8-四氢类球烯、3，4，5，6-四氢类球烯、3，4-二氢类球烯和类球烯的结果一起（Frank，H.一、Farhoosh，R.; Aldema，M. L.的; DeCoster，B.;克里斯滕森河，巴西-地L.的; Gebhard，R.; Lugtenburg，J. Photochem.光生物学1993年，57，49。Farhoosh，R.; Chynwat，V.; Gebhard，R.; Lugtenburg，J.;弗兰克，H。A.光合作用。Res. 1994，42，157），提供了一系列系统的分子，用于理解决定光合细菌捕光复合物中从类胡萝卜素到BChl的能量转移机制的分子特征。数据支持这样的假设，即只有具有10个或更少碳-碳双键的类胡萝卜素通过其2（1）A（g）（S-1）状态将能量转移到BChl到任何显著程度。随着共轭碳-碳双键数目的增加，通过类胡萝卜素的1（1）B（u）（S-2）状态的能量转移变得比S-1途径更重要。结果还表明，与B850 BChl的Q（x）跃迁相关的S-2态是所有类胡萝卜素的2（1）A（g）（S-1）和1（1）B（u）（S-2）态的能量转移最可能的受体态。
Spheroidene and a series of spheroidene analogues with extents of pi-electron conjugation ranging from 7 to 13 carbon-carbon double bonds were Incorporated into the B850 light-harvesting complex of Rhodobacter sphaeroides R-26.1. The structures and spectroscopic properties of the carotenoids and the dynamics of energy transfer from the carotenoid to bacteriochlorophyll (BChl) in the B850 complex were studied by using steady-state absorption, fluorescence, fluorescence excitation, resonance Raman, and time-resolved absorption spectroscopy. The spheroidene analogues used in this study were 5',6'- dihydro-7',8'-didehydrospheroidene, 7',8'-didehydrospheroidene, and 1',2'-dihydro-3',4',7',8'-tetradehydrospheroidene. These data, taken together with results from 3,4,7,8-tetrahydsospheroidene, 3,4,5,6-tetrahydrospheroidene, 3,4-dihydrospheroidene, and spheroidene already published (Frank, H. A.; Farhoosh, R.; Aldema, M. L.; DeCoster, B.; Christensen, R. L.; Gebhard, R.; Lugtenburg, J. Photochem. Photobiol. 1993, 57, 49. Farhoosh, R.; Chynwat, V.; Gebhard, R.; Lugtenburg, J.; Frank, H. A. Photosynth. Res. 1994, 42, 157), provide a systematic series of molecules for understanding the molecular features that determine the mechanism of energy transfer from carotenoids to BChl in photosynthetic bacterial light-harvesting complexes. The data support the hypothesis that only carotenoids having 10 or less carbon-carbon double bonds transfer energy via their 2(1)A(g) (S-1) states to BChl to any significant degree. Energy transfer via the 1(1)B(u) (S-2) State of the carotenoid becomes more important than the S-1 route as the number of conjugated carbon-carbon double bonds increases. The results also suggest that the S-2 state associated with the Q(x) transition of the B850 BChl is the most likely acceptor state for energy transfer originating from both the 2(1)A(g) (S-1) and 1(1)B(u) (S-2) states of all carotenoids.