Organization of porphyrin derivatives using photosynthetic light-havesting polypeptide and its model polypeptide

光合细菌的捕光（LH）-a和-B多肽根据LH多肽和BChla之间的协同相互作用在生物膜中组织细菌叶绿素a（BChla）复合物，使得细菌叶绿素之间的有效能量转移可以在LH复合物中发生。来自几个实验室的工作已经证明了通过使用合成多肽来组织人工血红素蛋白模型的卟啉的自组装。然而，通过使用合成多肽来组织人工LH复合物的叶绿素分子组装的研究很少。在这里，细菌叶绿素a（BChl a）及其模型化合物的分子组装体使用分别从光合细菌红色红螺菌（Rhodospillum rubrum）（Rsp. rubrum）及其模型合成多肽在脂质双层以及n-辛基-b-D-吡喃葡萄糖苷（OG）胶束中进行了检测。比较LH多肽及其模型肽与Zn-BChl a或BChl a形成复合物的N-和C-末端区段中的氨基酸序列，揭示LH多肽的N-末端区段中从M到F的氨基酸残基基本上解释了Zn-BChl a和BChl a之间形成复合物的差异。有趣的是，观察到BChla及其模型化合物使用LH多肽及其模型多肽在脂质双层中的自组装，类似于人工LH 1型复合物。有趣的是，注意到BChla及其类似物复合物可以根据LH多肽或其模型多肽与细菌叶绿素衍生物之间的协同相互作用来组织。

The light-harvesting (LH) -a and -b polypeptides of photosynthetic bacteria organize a bachteriochlorophyll a (BChl a) complex according to cooperative interactions between the LH polypeptides and BChl a in a biologial membrane so that an efficient energy transfer between bacteriochlorophylls may occur in the LH complex. Work from several laboratories has demonstrated self-assemblies of porphyrins by using synthetic polypeptides to organize artificial hemoprotein models. However, there has been little study of molecular assembly of chlorophylls by using synthetic polypeptides to organize an artificial LH complex. Here, molecular assemblies of bacteriochloropyll a (BChl a) and its model compounds using light-harvesting (LH) polypeptide separately isolated from photosynthetic bacteria, Rhodospirllum rubrum (Rsp. rubrum) and its model synthetic polypeptides were examined in lipid bilayers as well as in n-Octyl-b-D-glucopyranoside (OG) micelle. Comparing the amino acid sequence in the N-and C-terminal segments of the LH polypeptide and its model peptides on the complex-formation with Zn-BChl a or BChl a reveals that the amino acid residues from M to F in the N-terminal segment of the LH polypeptide essentially account for the difference in the complex-formation between Zn-BChl a and BChl a. Interestingly, self-assembly of BChl a and its model compounds using the LH polypeptide and its model polypeptides in lipid bilayers was observed, analogous to an artificial LH 1-type complex. It is interesting to note that BChl a and its analogues complexes can be organized according to cooperative interactions between the LH polypeptide or its model polypeptides and bachteriochlorophyll derivatives.