Montaño Gabriel A, Wu Hsing-Mei, Lin Su, Brune Daniel C, Blankenship Robert E
Graduate Program in Molecular and Cellular Biology, Arizona State University, Tempe, Arizona 85287-1604, USA.
Biochemistry. 2003 Sep 2;42(34):10246-51. doi: 10.1021/bi034350k.
The B798 light-harvesting baseplate of the chlorosome antenna complex of the thermophilic, filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus has been isolated and characterized. Isolation was performed by using a hexanol-detergent treatment of freeze-thawed chlorosomes. The isolated baseplate consists of Bchl a, beta-carotene, and the 5.7 kDa CsmA protein with a ratio of 1.0 CsmA protein/1.6 Bchl a/4.2 beta-carotenes. The baseplate has characteristic absorbance at 798 nm as well as carotenoid absorbance maxima at 519, 489, and 462 nm. The energy transfer efficiency from the carotenoids to the Bchl a is 30% as measured by steady-state and ultrafast time-resolved fluorescence and absorption spectroscopies. Energy equilibration within the Bchl a absorbing regions exhibits ultrafast kinetics. Circular dichroism spectroscopy shows no evidence for excitonically coupled Bchl a pools within the 798 nm region.
嗜热丝状厌氧光合细菌嗜热栖热菌（Chloroflexus aurantiacus）的叶绿体天线复合物的B798光捕获基板已被分离并表征。通过对冻融的叶绿体进行己醇 - 去污剂处理来进行分离。分离出的基板由细菌叶绿素a（Bchl a）、β-胡萝卜素和5.7 kDa的CsmA蛋白组成，其比例为1.0 CsmA蛋白/1.6 Bchl a/4.2β-胡萝卜素。该基板在798 nm处有特征吸收峰，在519、489和462 nm处有类胡萝卜素吸收最大值。通过稳态和超快时间分辨荧光及吸收光谱法测量，从类胡萝卜素到Bchl a的能量转移效率为30%。在Bchl a吸收区域内的能量平衡表现出超快动力学。圆二色光谱表明在798 nm区域内没有激子耦合的Bchl a池的证据。
