Ultrafast energy transfer dynamics of phycobilisome from Thermosynechococcus vulcanus, as revealed by ps fluorescence and fs pump-probe spectroscopies
Ultrafast energy transfer dynamics of phycobilisome from Thermosynechococcus vulcanus, as revealed by ps fluorescence and fs pump-probe spectroscopies
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DOI：
10.1007/s11120-021-00844-0
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发表时间：
2021-05-17
影响因子：
3.7
通讯作者：
Kosumi, Daisuke
中科院分区：
文献类型：
--
作者：
Hirota, Yuma;Serikawa, Hiroki;Kosumi, Daisuke
蓝藻光合系统利用色素蛋白巨复合物藻胆体（phycobilisome，PBS）有效地捕获阳光。能量随后转移到光系统I（PSI）和II（PSII），以产生电化学电势。在本研究中，我们进行了皮秒（ps）的时间分辨荧光和飞秒（fs）泵浦探测光谱的完整的PBS从嗜热蓝细菌，Thermosynechococcus vulcanus，揭示激发能量转移动力学在PBS。完整的PBS的光物理性质的光谱测量覆盖了从飞秒到纳秒的宽的时间范围内，其特征在于。在570 nm处激发的ps荧光测量，对应于藻蓝蛋白（PC）吸收带的较高能量，证明了从PC棒到别藻蓝蛋白（APC）核心复合物的激发能量转移以及APC核心复合物中的能量转移。然后，飞秒泵浦-探测测量揭示了PC棒中发生在超快时间尺度上的详细能量转移动力学。实验结果显示了漏斗型激发能转移的全貌，其速率常数为（0.57 ps）（-1）->（7.3 ps）（-1）->（53 ps）（-1）->（180 ps）（-1）->（1800 ps）（-1）.
Cyanobacterial photosynthetic systems efficiently capture sunlight using the pigment-protein megacomplexes, phycobilisome (PBS). The energy is subsequently transferred to photosystem I (PSI) and II (PSII), to produce electrochemical potentials. In the present study, we performed picosecond (ps) time-resolved fluorescence and femtosecond (fs) pump-probe spectroscopies on the intact PBS from a thermophilic cyanobacterium, Thermosynechococcus vulcanus, to reveal excitation energy transfer dynamics in PBS. The photophysical properties of the intact PBS were well characterized by spectroscopic measurements covering wide temporal range from femtoseconds to nanoseconds. The ps fluorescence measurements excited at 570 nm, corresponding to the higher energy of the phycocyanin (PC) absorption band, demonstrated the excitation energy transfer from the PC rods to the allophycocyanin (APC) core complex as well as the energy transfer in the APC core complex. Then, the fs pump-probe measurements revealed the detailed energy transfer dynamics in the PC rods taking place in an ultrafast time scale. The results obtained in this study provide the full picture of the funnel-type excitation energy transfer with rate constants of (0.57 ps)(-1) -> (7.3 ps)(-1) -> (53 ps)(-1) -> (180 ps)(-1) -> (1800 ps)(-1).