Excitation energy transfer between the B850 and B875 antenna complexes of Rhodobacter sphaeroides
Excitation energy transfer between the B850 and B875 antenna complexes of Rhodobacter sphaeroides
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DOI：
10.1021/bi962534b
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发表时间：
1997-02-25
期刊：
影响因子：
2.9
通讯作者：
Parson, WW
中科院分区：
文献类型：
--
作者：
Nagarajan, V;Parson, WW
利用飞秒泵浦-探测光谱技术研究了室温下无反应中心的类球杆藻突变株B850（LH 2）和B875（LH 1）天线复合物之间的能量传递.在B850或B875的选择性激发后，在810和910 nm之间的波长下进行测量，时间延伸到200 ps。基于除了反应中心之外还缺乏LH 1或LH 2的菌株中的测量，对两种类型的天线复合物的光谱信号进行测量。从激发的B850到B875的能量转移以两个时间常数进行，4.6+/-0.3和26.3+/-1.0 ps，但是很大一部分激发保持在B850中相当长的时间。快的步骤被解释为跳跃的能量从相关的LH 2复杂的LH 1;较慢的步骤被解释为迁移的激发在LH 2池之前转移到LH 1。不能检测到从B875到B850的激发转移，这可能表明与每个LH 1接触的LH 2复合物的平均数量很小。
Energy transfer between the B850 (LH2) and B875 (LH1) antenna complexes of a mutant strain of Rhadobacter sphaeroides lacking reaction centers is investigated by femtosecond pump-probe spectroscopy at room temperature. Measurements are made at wavelengths between 810 and 910 nm at times extending to 200 ps after selective excitation of either B850 or B875, Assignments of the spectroscopic signals to the two types of antenna complex are made on the basis of measurements in strains that lack either LH1 or LH2 in addition to reaction centers. Energy transfer from excited B850 to B875 proceeds with two time constants, 4.6+/-0.3 and 26.3+/-1.0 ps, but a significant fraction of the excitations remain in B850 for considerably longer times. The fast step is interpreted as hopping of energy to LH1 from an associated LH2 complex; the slower steps are interpreted as migration of excitations in the LH2 pool preceding transfer to LH1. Transfer of excitations from B875 to B850 could not be detected, possibly suggesting that the average number of LH2 complexes in contact with each LH1 is small.