Excitation energy transfer (EET) and trapping in Anabaena variabilis (PCC 7120) intact cells, isolated phycobilisomes (PBS) and photosystem I (PSI) complexes have been studied by picosecond time-resolved fluorescence spectroscopy at room temperature. Global analysis of the time-resolved fluorescence kinetics revealed two lifetimes of spectral equilibration in the isolated PBS, 30-35 ps and 110-130 ps, assigned primarily to energy transfer within the rods and between the rods and the allophycocyanin core, respectively. An additional intrinsic kinetic component with a lifetime of 500-700 ps was found, representing non-radiative decay or energy transfer in the core. Isolated tetrameric PSI complexes exhibited biexponential fluorescence decay kinetics with lifetimes of about 10 ps and 40 ps, representing equilibration between the bulk antenna chlorophylls with low-energy "red" states and trapping of the equilibrated excitations, respectively. The cascade of EET in the PBS and in PSI could be resolved in intact filaments as well. Virtually all energy absorbed by the PBS was transferred to the photosystems on a timescale of 180-190 ps.

中文翻译：

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蓝藻鱼腥藻 PCC 7120 中激发能量转移的时间分辨荧光研究。


在室温下通过皮秒时间分辨荧光光谱研究了多变鱼腥藻 (PCC 7120) 完整细胞、分离藻胆体 (PBS) 和光系统 I (PSI) 复合物中的激发能量转移 (EET) 和捕获。时间分辨荧光动力学的全局分析揭示了分离的 PBS 中的两个光谱平衡寿命，30-35 ps 和 110-130 ps，分别主要分配给棒内以及棒与别藻蓝蛋白核心之间的能量转移。还发现了一个寿命为 500-700 ps 的额外内在动力学成分，代表核心中的非辐射衰变或能量转移。分离的四聚体 PSI 复合物表现出双指数荧光衰变动力学，寿命约为 10 ps 和 40 ps，分别代表具有低能量“红色”态的体状天线叶绿素之间的平衡和平衡激发的捕获。 EET 在 PBS 和 PSI 中的级联也可以在完整的细丝中解析。事实上，PBS 吸收的所有能量都以 180-190 ps 的时间尺度转移到光系统。