PHOTOSYNTHETIC REACTION CENTER MAQUETTE

模型是基于蛋白质的简化合成版本 结构. 肽的从头合成的进展介绍了 有机会构建化学上简单的肽， 生物氧化还原位点，使我们能够观察分子 工程参与其组装，并建立最低限度的 其高度复杂的自然功能的要求 同行 [CPP-? 2]2蛋白质（CPP =粪卟啉I，？= CGGGELWKLHEELLKKFEELL-KLHEERLKKL-CONH 2）是一个模型， 光合反应中心（PRC），由四个相同的 两栖动物？螺旋与CPP二聚体单元共价连接， N的末端。 它是基于我们以前的工作（自然368， 425-432，1994），并且能够结合多达四个血红素单元。 二聚体 卟啉模拟PRC中的特殊对，而双His结合 血红素是Bchl和Bph的模型。我们正在调查 [CPP-？2]2在缓冲溶液中， 具有12.0ns的荧光寿命，0.06的峰值各向异性， 旋转相关时间为5.2ns（？ex=398 nm和？em =620 nm）。 相比之下，缓冲液中的游离CCP表现出荧光发射5 倍以上（在相同的OD作为[CPP-？2]2)寿命为15.5 ns (30%长）和0.14的峰值各向异性和0.15的旋转取向。 相关时间为0.083 ns。 这些结果表明，我们 实际上测量与肽结合的CPP的发射， 假设为球形，估计分子直径为36 E。

Maquettes are simplified synthetic versions of protein based structures. Progress with de novo synthesis of peptides presents the opportunity to construct chemically simple peptides that incorporate biological redox sites, permitting us to view the molecular engineering involved in their assembly and to establish the minimal requirements for function of their highly complex natural counterparts. [CPP-?2]2 protein (CPP = coproporphyrin I, ? = CGGGELWKLHEELLKKFEELL-KLHEERLKKL-CONH2) is a maquette for the Photosynthetic Reaction Center (PRC) and consist of four identical amphipatic ?-helixes with a CPP dimeric unit appended covalently to the N terminus. It is based in our previous work (Nature 368, 425-432, 1994) and is able to bind up to four heme units. The dimeric porphyrin mimics the special pair in the PRC whereas the bis-His bound hemes are a model for Bchl and Bph. We are investigating the fluorescence emission properties of [CPP-?2]2 in buffer solution which has a fluorescence lifetime of 12.0 ns, a peak anisotropy of 0.06 and a rotational correlation time of 5.2 ns (?ex=398 nm and ?em =620 nm). In contrast, free-CCP in buffer exhibits a fluorescence emission 5 times greater (at the same OD as [CPP-?2]2)with a lifetime of 15.5 ns (30% longer) and a peak anisotropy of 0.14 and a rotational correlation time of 0.083 ns. These results indicate that we are indeed measuring the emission of CPP bound to the peptide and we could estimate a molecular diameter of 36 E assuming a spherical shape.