Department of Chemical Physics, Lund University, P.O. Box 124, SE-22 100, Lund, Sweden.
J Phys Chem B. 2011 May 5;115(17):4963-70. doi: 10.1021/jp107480x. Epub 2011 Apr 12.
Excitation and emission polarization dependence of fluorescence intensity of single LH2 complexes from Rhodopseudomonas acidophila 10050 and Rhodobacter sphaeroides is reported. The results are presented as two-dimensional polarization plots and interpreted in terms of tilted light harvesting complexes indicating that sample preparation leads to partially oriented LH2 cylinders. An alternative explanation of the observation can be structural deformation. Fluorescence intensity of the complexes has four qualitatively distinct excitation-emission polarization dependencies. The differences in excitation polarization dependence are interpreted as due to the tilt of the complexes, whereas the emission polarization behavior is mainly determined by spectral inhomogeneity of the emitting B850 ring. Some complexes show abrupt reversible variations of the total emission intensity together with changes of the polarization properties which cannot be described by the simplest model of tilted LH2s with spectral disorder.
报道了嗜酸红假单胞菌 10050 和球形红杆菌的单个 LH2 复合物的荧光强度的激发和发射偏振依赖性。结果以二维偏振图呈现，并根据倾斜的光收集复合物进行解释，表明样品制备导致 LH2 圆柱部分取向。观察结果的另一种解释可能是结构变形。复合物的荧光强度具有四种定性不同的激发-发射偏振依赖性。激发偏振依赖性的差异解释为复合物的倾斜，而发射偏振行为主要由发射 B850 环的光谱非均匀性决定。一些复合物显示出总发射强度的突然可逆变化以及偏振特性的变化，这不能用具有光谱无序的倾斜 LH2 的最简单模型来描述。
