The X-ray crystal structure of the LH2 complex from Rhodospeudomonas acidophila strain 10050 has been determined to a resolution of ~2A [1]. This structure shows that the complex contains two rings of bacteriochlorophyll molecules. One ring consists of nine largely monomeric bacteriochlorophylls separated by about 21A and the other has 18 tightly coupled, strongly interacting ones. The molecules in the monomeric ring have their Qy absorption band at 800 nm while those in the tightly coupled ring their Qy absorption band at ~850 nm [2]. Single molecule spectroscopy has proved to be very useful in helping to provide the best physical description of the origin of these absorption bands [3]. This is fundamental information that is required to understand the detailed mechanisms of energy transfer that take place within these light harvesting complexes.[1] M. Z. Papiz et al. J. Mol. Biol. 326 , (2003), 1523.[2] A. A. Freer et al. Structure, 4 , (1996), 449.[3] R. J. Cogdell et al. Quart. Rev. in Biophys. 39 , (2006), 227.

Using single molecule spectroscopy to gain a better understanding of the spectroscopy of LH2 complexes from purple photosynthetic bacteria

243rd National Meeting (2012)

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