Fetisova Z, Freiberg A, Mauring K, Novoderezhkin V, Taisova A, Timpmann K
A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
Biophys J. 1996 Aug;71(2):995-1010. doi: 10.1016/S0006-3495(96)79301-3.
A theory of excitation energy transfer within the chlorosomal antennae of green bacteria has been developed for an exciton model of aggregation of bacteriochlorophyll (BChl) c (d or e). This model of six exciton-coupled BChl chains with low packing density, approximating that in vivo, and interchain distances of approximately 2 nm was generated to yield the key spectral features found in natural antennae, i.e., the exciton level structure revealed by spectral hole burning experiments and polarization of all the levels parallel to the long axis of the chlorosome. With picosecond fluorescence spectroscopy it was demonstrated that the theory explains the antenna-size-dependent kinetics of fluorescence decay in chlorosomal antenna, measured for intact cells of different cultures of the green bacterium C. aurantiacus, with different chlorosomal antenna size determined by electron microscopic examination of the ultrathin sections of the cells. The data suggest a possible mechanism of excitation energy transfer within the chlorosome that implies the formation of a cylindrical exciton, delocalized over a tubular aggregate of BChl c chains, and Forster-type transfer of such a cylindrical exciton between the nearest tubular BChl c aggregates as well as to BChl a of the baseplate.
针对细菌叶绿素（BChl）c（d或e）聚集的激子模型，已建立了绿细菌叶绿体天线内激发能转移理论。该模型由六条激子耦合的BChl链组成，堆积密度低，近似于体内情况，链间距离约为2 nm，旨在产生天然天线中发现的关键光谱特征，即光谱烧孔实验揭示的激子能级结构以及所有能级平行于叶绿体长轴的极化。通过皮秒荧光光谱证明，该理论解释了叶绿体天线中荧光衰减的天线大小依赖性动力学，这是针对橙色绿菌不同培养物的完整细胞测量的，不同培养物的叶绿体天线大小通过对细胞超薄切片的电子显微镜检查确定。数据表明了叶绿体中激发能转移的一种可能机制，这意味着形成一个圆柱形激子，其在BChl c链的管状聚集体上离域，以及这种圆柱形激子在最近的管状BChl c聚集体之间以及向基板的BChl a进行福斯特型转移。
