Single-Molecule Studies on Purple Bacterial Antenna Complexes

紫色细菌光合作用的主要反应发生在两个色素蛋白复合物中，即外周LH 2复合物和核心RC-LH 1复合物。为了理解LH系统中任何类型的激发能量转移，关于几何结构和电子激发态性质之间的相关性的详细知识是至关重要的。颜料的几何排列和各种激子态的跃迁概率之间的相互作用导致了关键的光谱特征，例如窄线，这些特征在单分子光谱学中清晰可见，但在传统的系综实验中被平均化。该项目是生物化学和物理学之间的合作努力。结合生物化学制剂，单分子光谱和计算机模拟，我们希望研究来自各种物种的单个LH 2和RC-LH 1复合物，其中没有或只有很少的结构信息。该项目的目的是更深入地了解天线复合体光谱形式自然变化范围的结构基础，这是深入讨论它们所参与的能量转移的可能机制实际运作的必要先决条件。

The primary reactions of purple bacterial photosynthesis take place in two pigmentprotein complexes, the peripheral LH2 complex and the core RC-LH1 complex. In order to understand any type of excitation-energy transfer in the LH system detailed knowledge about the correlation between the geometrical structure and the nature of the electronically excited states is crucial. The interplay between the geometrical arrangement of the pigments and the transition probabilities of the various exciton states leads to key spectral features, such as narrow lines, that are clearly visible with single-molecule spectroscopy but are averaged out in conventional ensemble experiments. This project is a collaborative effort between biochemistry and physics. Combining biochemical preparations, single-molecule spectroscopy and computer simulations we want to investigate individual LH2 and RC-LH1 complexes from various species where no or only little structural information is available as yet. Aim of this project is to develop a deeper understanding of the structural basis of the range of natural variation of the spectroscopic forms of the antenna complexes which is an essential prerequisite for an in-depth discussion of which of the possible mechanisms of energy transfer, in which they are engaged, actually operate.