Single-Molecule Studies on Purple Bacterial Antenna Complexes

• Applicant: Professor Dr. Jürgen Köhler
• Subject Area: Biophysics
• Term: from 2008 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 81329493

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.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Participating Person: Professor Dr. Richard Cogdell