Dark States in the Light-Harvesting complex 2 Revealed by Two-dimensional Electronic Spectroscopy.
Dark States in the Light-Harvesting complex 2 Revealed by Two-dimensional Electronic Spectroscopy.
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DOI：
10.1038/srep20834
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发表时间：
2016-02-09
影响因子：
4.6
通讯作者：
van Grondelle R
中科院分区：
文献类型：
--
作者：
Ferretti M;Hendrikx R;Romero E;Southall J;Cogdell RJ;Novoderezhkin VI;Scholes GD;van Grondelle R
紫色光合细菌捕光触角中的能量传递和捕获是一个超快过程，其量子效率接近1。然而，这一过程背后的机制尚未得到充分理解。最近有人提出，低能暗态，如电荷转移态和极化子对，在能量转移的动力学和方向性中起着重要作用。然而，由于它们的跃迁偶极矩小，并且与B850/B870激子带重叠，因此很难直接检测到这些态。在这里，我们提出了一种新的实验方法，它结合了二维电子光谱的选择性与遗传修饰的捕光复合物的可用性，揭示了这些黑暗的状态中存在的遗传修饰和野生型捕光2复合物的沼泽红蜻蜓。我们认为，大自然已经使用了不可避免的电荷转移过程时，LH颜料集中，以提高和指导能量的流动。
Energy transfer and trapping in the light harvesting antennae of purple photosynthetic bacteria is an ultrafast process, which occurs with a quantum efficiency close to unity. However the mechanisms behind this process have not yet been fully understood. Recently it was proposed that low-lying energy dark states, such as charge transfer states and polaron pairs, play an important role in the dynamics and directionality of energy transfer. However, it is difficult to directly detect those states because of their small transition dipole moment and overlap with the B850/B870 exciton bands. Here we present a new experimental approach, which combines the selectivity of two-dimensional electronic spectroscopy with the availability of genetically modified light harvesting complexes, to reveal the presence of those dark states in both the genetically modified and the wild-type light harvesting 2 complexes of Rhodopseudomonas palustris. We suggest that Nature has used the unavoidable charge transfer processes that occur when LH pigments are concentrated to enhance and direct the flow of energy.