Interexciton nonradiative relaxation pathways in the peridinin-chlorophyll protein
Interexciton nonradiative relaxation pathways in the peridinin-chlorophyll protein
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DOI：
10.1016/j.xcrp.2021.100380
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发表时间：
2021-03-24
影响因子：
8.9
通讯作者：
Beck, Warren F.
中科院分区：
文献类型：
--
作者：
Tilluck, Ryan W.;Ghosh, Soumen;Beck, Warren F.
当被分子激子介导时，激发能传递可以异常高效和结构稳健。当电子发色团在吸收光时产生离域激发时，在光合作用的光收集蛋白中产生激子。在这里，我们报告了二维电子光谱和电子结构计算的结果，揭示了激发能在海洋鞭毛藻的橄榄藻-叶绿素蛋白中的橄榄藻素和叶绿素激子之间通过一个离域的两步途径传递。在强、中可见吸收带中，橄榄苷吸收光后，激发能在室温下被叶绿素捕获，时间不超过50fs。当叶绿素a被叶绿素b取代时，整个过程只会被减缓几秒。该途径的关键步骤是将激发从具有更广泛离域的高能量周胞素激子转移到最低能量的周胞素激子，该激子仅在周胞素614和邻近叶绿素上离域。
Excitation energy transfer can be unusually efficient and structurally robust when mediated by molecular excitons, which arise in a photosynthetic light-harvesting protein when delocalized excitations of the electronic chromophores are created upon absorption of light. Here we report results from two-dimensional electronic spectroscopy and electronic structure calculations, revealing that excitation energy is transferred between the peridinin and chlorophyll excitons in the peridinin-chlorophyll protein from marine dinoflagellates over a delocalized, two-step pathway. Upon absorption of light by the peridinins in the strong, mid-visible absorption band, excitation energy is trapped by the chlorophylls in less than 50 fs at room temperature. The overall process is slowed only by a few fs upon replacement of chlorophyll a with chlorophyll b. The key step in the pathway transfers excitation from higher-energy peridinin excitons with more extensive delocalization to the lowest-energy peridinin exciton, which is delocalized only over peridinin 614 and the neighboring chlorophyll.