Ferretti Marco, Hendrikx Ruud, Romero Elisabet, Southall June, Cogdell Richard J, Novoderezhkin Vladimir I, Scholes Gregory D, van Grondelle Rienk
Department of Physics and Astronomy, VU University, 1081 HV Amsterdam, The Netherlands.
Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
Sci Rep. 2016 Feb 9;6:20834. doi: 10.1038/srep20834.
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.
紫色光合细菌光捕获天线中的能量转移和俘获是一个超快过程，其发生时的量子效率接近1。然而，这一过程背后的机制尚未完全被理解。最近有人提出，诸如电荷转移态和极化子对等低能暗态在能量转移的动力学和方向性中起着重要作用。然而，由于这些态的跃迁偶极矩小且与B850/B870激子带重叠，难以直接检测到它们。在此，我们提出一种新的实验方法，该方法将二维电子光谱的选择性与基因改造的光捕获复合物的可用性相结合，以揭示在沼泽红假单胞菌的基因改造和野生型光捕获2复合物中这些暗态的存在。我们认为，大自然利用了LH色素集中时不可避免发生的电荷转移过程来增强和引导能量流动。
