Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic; Institute of Plant Molecular Biology, Biological Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.
Biochim Biophys Acta Bioenerg. 2018 May;1859(5):357-365. doi: 10.1016/j.bbabio.2018.02.011. Epub 2018 Feb 27.
We have applied femtosecond transient absorption spectroscopy in pump-probe and pump-dump-probe regimes to study energy transfer between fucoxanthin and Chl a in fucoxanthin-Chl a complex from the pennate diatom Phaeodactylum tricornutum. Experiments were carried out at room temperature and 77 K to reveal temperature dependence of energy transfer. At both temperatures, the ultrafast (<100 fs) energy transfer channel from the fucoxanthin S state is active and is complemented by the second pathway via the combined S/ICT state. The S/ICT-Chl a pathway has two channels, the fast one characterized by sub-picosecond energy transfer, and slow having time constants of 4.5 ps at room temperature and 6.6 ps at 77 K. The overall energy transfer via the S/ICT is faster at 77 K, because the fast component gains amplitude upon lowering the temperature. The pump-dump-probe regime, with the dump pulse centered in the spectral region of ICT stimulated emission at 950 nm and applied at 2 ps after excitation, proved that the S and ICT states of fucoxanthin in FCP are individual, yet coupled entities. Analysis of the pump-dump-probe data suggested that the main energy donor in the slow S/ICT-Chl a route is the S part of the S/ICT potential surface.
我们应用飞秒瞬态吸收光谱技术在泵浦-探测和泵浦-探测-探测两种模式下，研究了从舟形藻（Phaeodactylum tricornutum）中提取的岩藻黄质-叶绿素 a 复合体系中岩藻黄质和叶绿素 a 之间的能量转移。实验在室温（298 K）和 77 K 下进行，以揭示温度对能量转移的影响。在这两种温度下，来自岩藻黄质 S 态的超快（<100 fs）能量转移通道是活跃的，并且由 S/ICT 态的组合态来补充。S/ICT-叶绿素 a 途径有两个通道，其中一个快速通道的能量转移时间常数为亚皮秒，另一个慢速通道的时间常数在室温下为 4.5 ps，在 77 K 下为 6.6 ps。由于低温下快速组分的幅度增加，通过 S/ICT 的整体能量转移在 77 K 下更快。泵浦-探测-探测模式中，探测脉冲的中心位于 ICT 受激辐射的光谱区域（950nm），在激发后 2 ps 施加，证明了 FCP 中岩藻黄质的 S 和 ICT 态是独立的，但相互耦合的实体。对泵浦-探测-探测数据的分析表明，在慢速 S/ICT-叶绿素 a 途径中，主要的能量供体是 S/ICT 势能面的 S 部分。
