Ketelaars M, Kohler J, Aartsma TJ, Schmidt J
Centre for the Study of Excited States of Molecules, Department of Biophysics, Huygens Laboratory, Leiden University, Post Office Box 9504, 2300 RA Leiden, Netherlands.
Science. 1999 Jul 16;285(5426):400-2. doi: 10.1126/science.285.5426.400.
Low-temperature single-molecule spectroscopic techniques were applied to a light-harvesting pigment-protein complex (LH2) from purple photosynthetic bacteria. The properties of the electronically excited states of the two circular assemblies (B800 and B850) of bacteriochlorophyll a (BChl a) pigment molecules in the individual complexes were revealed, without ensemble averaging. The results show that the excited states of the B800 ring of pigments are mainly localized on individual BChl a molecules. In contrast, the absorption of a photon by the B850 ring can be consistently described in terms of an excitation that is completely delocalized over the ring. This property may contribute to the high efficiency of energy transfer in these photosynthetic complexes.
低温单分子光谱技术被应用于紫色光合细菌的捕光色素-蛋白复合物（LH2）。在没有系综平均的情况下，揭示了单个复合物中细菌叶绿素a（BChl a）色素分子的两个环状聚集体（B800和B850）的电子激发态性质。结果表明，色素B800环的激发态主要定域在单个BChl a分子上。相比之下，B850环吸收光子的过程可以用一种完全离域于环上的激发来一致地描述。这一性质可能有助于这些光合复合物中能量转移的高效率。
