Department of Biophysics, Huygens Laboratory of the State University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands.
Photosynth Res. 1986 Jan;9(1-2):33-45. doi: 10.1007/BF00029729.
The transfer of excitation energy and the pigment arrangement in isolated chlorosomes of the thermophilic green bacterium Chloroflexus aurantiacus were studied by means of absorption, fluorescence and linear dichroism spectroscopy, both at room temperature and at 4 K. The low temperature absorption spectrum shows bands of the main antenna pigments BChl c and carotenoid, in addition to which bands of BChl a are present at 798 and 613 nm. Fluorescence measurements showed that excitation energy from BChl c and carotenoid is transferred to BChl a, which presumably functions as an intermediate in energy transfer from the chlorosome to the cytoplasmic membrane. Measurements of fluorescence polarization and the use of two different orientation techniques for linear dichroism experiments enabled us to determine the orientation of several transition dipole moments with respect to each other and to the three principal axes of the chlorosome. The Qy transition of BChl a is oriented almost perfectly perpendicular to the long axis of the chlorosome. The Qy transition of BChl c and the γ-carotene transition dipole are almost parallel to each other. They make an angle of about 40° with the long axis and of about 70° with the short axis of the chlorosome; the angle between these transitions and the BChl a Qy transition is close to the magic angle (55°).
采用吸收光谱、荧光光谱和线性二色性光谱法，在室温及 4 K 条件下，研究了嗜热绿菌（Chloroflexus aurantiacus）分离的叶绿素体中激发能量的转移和色素排列。低温吸收光谱显示，除了主要天线色素 BChl c 和类胡萝卜素的谱带外，还存在 798nm 和 613nm 处的 BChl a 谱带。荧光测量表明，BChl c 和类胡萝卜素的激发能量转移到 BChl a，BChl a 可能在从叶绿素体到细胞质膜的能量转移中起中间作用。荧光偏振测量和两种不同的线性二色性实验取向技术的使用，使我们能够确定几个跃迁偶极子相对于彼此和叶绿素体的三个主轴的取向。BChl a 的 Qy 跃迁几乎垂直于叶绿素体的长轴取向。BChl c 的 Qy 跃迁和 γ-胡萝卜素跃迁偶极子几乎相互平行。它们与叶绿素体的长轴形成约 40°的角度，与短轴形成约 70°的角度；这些跃迁与 BChl a Qy 跃迁之间的角度接近魔角（55°）。
