Zurdo J, Lozano R M, Fernandez-Cabrera C, Ramirez J M
Centro de Investigaciones Biológicas del C.S.I.C., Velázquez, Madrid, Spain.
Biochem J. 1991 Mar 15;274 ( Pt 3)(Pt 3):881-4. doi: 10.1042/bj2740881.
The carotenoid content of intracytoplasmic membrane vesicles isolated from purple phototrophic bacteria was reduced to a variable extent by mild extraction with light petroleum. Using preparations obtained from Rhodobacter capsulatus strains that contained the Light Harvesting System I (LHI) complex as the only major photosynthetic holochrome, it was shown that the visible circular dichroism of the carotenoids increased with the square of the membrane carotenoid content, as expected from being caused by dimeric exciton interaction. No chirality resulting from twists of the individual planar chromophore was detected. Therefore the contribution to carotenoid optical activity of non-degenerate interactions with bacteriochlorophyll or the apoprotein does not appear to be significant. The broadening of the absorption band of the bound pigment, caused by the splitting of the monomer transition, was demonstrated in membrane vesicles of both Rb, capsulatus and Rhodospirillum rubrum as a decrease of the fine structure of the band. Furthermore, the dimeric organization of the carotenoid pigments in the bacterial LHI complex accounted for the observed quantitative relationship between the fine structure of the band and the carotenoid content of the membrane.
用轻质石油进行温和萃取后，从紫色光合细菌中分离出的胞质内膜囊泡中的类胡萝卜素含量会有不同程度的降低。使用从含有光捕获系统I（LHI）复合物作为唯一主要光合全色素的荚膜红细菌菌株中获得的制剂，结果表明，类胡萝卜素的可见圆二色性随膜类胡萝卜素含量的平方增加，这正如由二聚体激子相互作用所导致的预期情况。未检测到单个平面发色团扭曲产生的手性。因此，与细菌叶绿素或脱辅基蛋白的非简并相互作用对类胡萝卜素光学活性的贡献似乎并不显著。在荚膜红细菌和深红红螺菌的膜囊泡中，均证实了由单体跃迁分裂引起的结合色素吸收带变宽，表现为该带精细结构的减弱。此外，细菌LHI复合物中类胡萝卜素色素的二聚体组织解释了观察到的带精细结构与膜类胡萝卜素含量之间的定量关系。
