揭示别藻蓝蛋白中的暗多色态。
Uncovering dark multichromophoric states in Peridinin-Chlorophyll-Protein.
机构信息
Department of Chemistry, Princeton University, Washington Road, Princeton, NJ 08540, USA.
Department of Chemistry, University of Mons, 7000 Mons, Belgium.
出版信息
J R Soc Interface. 2020 Mar;17(164):20190736. doi: 10.1098/rsif.2019.0736. Epub 2020 Mar 18.
It has long been recognized that visible light harvesting in Peridinin-Chlorophyll-Protein is driven by the interplay between the bright (S) and dark (S) states of peridinin (carotenoid), along with the lowest-lying bright (Q) and dark (Q) states of chlorophyll-. Here, we analyse a chromophore cluster in the crystal structure of Peridinin-Chlorophyll-Protein, in particular, a peridinin-peridinin and a peridinin-chlorophyll- dimer, and present quantum chemical evidence for excited states that exist beyond the confines of single peridinin and chlorophyll chromophores. These dark multichromophoric states, emanating from the intermolecular packing native to Peridinin-Chlorophyll-Protein, include a correlated triplet pair comprising neighbouring peridinin excitations and a charge-transfer interaction between peridinin and the adjacent chlorophyll-. We surmise that such dark multichromophoric states may explain two spectral mysteries in light-harvesting pigments: the sub-200-fs singlet fission observed in carotenoid aggregates, and the sub-200-fs chlorophyll- hole generation in Peridinin-Chlorophyll-Protein.
一直以来，人们都认为在甲藻黄素-叶绿素蛋白中，可见光能的捕获是由甲藻黄素（类胡萝卜素）的明亮（S）态和黑暗（S）态与叶绿素的最低亮（Q）态和暗（Q）态之间的相互作用驱动的。在这里，我们分析了甲藻黄素-叶绿素蛋白晶体结构中的一个发色团簇，特别是一个甲藻黄素-甲藻黄素和一个甲藻黄素-叶绿素二聚体，并提出了超越单个甲藻黄素和叶绿素发色团限制的激发态的量子化学证据。这些来自于甲藻黄素-叶绿素蛋白本征的分子间堆积的暗多色激发态，包括由相邻甲藻黄素激发组成的相关三重态对和甲藻黄素与相邻叶绿素之间的电荷转移相互作用。我们推测，这些暗多色激发态可能解释了光捕获色素中的两个光谱之谜：在类胡萝卜素聚集体中观察到的亚 200fs 单线态裂变，以及在甲藻黄素-叶绿素蛋白中观察到的亚 200fs 叶绿素空穴生成。
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