SYNTHETIC PROBES OF HEME AND CHLOROPHYLL BIOCHEMISTRY

本提案涉及合成的 血红素和叶绿素蛋白的模型。 在 特别是，我们计划调查的作用，特别下令 在关键的生物过程中， 光合作用和电子传递。 我们已经开发出一种新 构建共价连接多个的策略 四吡咯之间具有不同的距离和取向， 戒指。 在本申请中，我们建议扩展这种方法 为了更紧密地模拟多个四吡咯位点的结构， 在生物学上。 我们的主要目标是四聚体和六聚体的类似物， 细菌光合反应中心的已知结构。 这些模型将分别包含二聚体-双（单体） 和二聚体-双（单体）-双（非金属化单体）结构 的反应中心。 通过改变使用的合成，我们将 能够产生一系列不同的化合物， 相关结构。 彻底的物理调查这些 衍生物，使用电化学，荧光和皮秒 光学技术，将提供光诱导的细节， 发生电子转移和电荷分离过程 在颜料之间。 这将使我们第一次 探讨发色团距离和方向对键的影响 光合作用过程的各个方面。 我们还将建立 作为比较的光活性氧化还原配偶体的简单线性阵列 到仿生模型。 在以后的模型化合物中，我们将 引入二氢卟酚和菌绿素大环化合物代替 卟啉结构单元。 这种类型的模型研究将导致 对蛋白质控制反应性的理解是至关重要的 用于解决与四吡咯相关的医学问题 生物化学

This proposal concerns the preparation and study of synthetic models of heme- and chlorophyll- containing proteins. In particular, we plan to investigate the role of specifically ordered aggregates to tetrapyrroles in such key biological processes as photosynthesis and electron transfer. We have developed a new strategy for the construction of covalently-linked multiple tetrapyrroles with different distances and orientations between the rings. In this application we propose to extend this approach to model more closely the structure of multiple tetrapyrrole sites in biology. Our primary targets are tetrameric and hexameric analogs of the known structure of bacterial photosynthetic reaction centers. These models will, respectively, contain the dimer-bis(monomer) and dimer-bis(monomer)-bis(non-metallated monomer) structure of the reaction centers. By varying the synthesis used we will be able to generate a series of compounds with different although related structures. Thorough physical investigation of these derivatives, using electrochemical, fluoresence and picosecond optical techniques, will provide details of the photoinduced electron transfer and charge separation processes occurring between the pigments. This will allow us, for the first time to probe the effect of chromophore distance and orientation on key aspects of the photosynthetic process. We will also construct simple linear arrays of photoactive redox partners as comparisons to the biomimetic models. In later model compounds we will introduce chlorin and bacteriochlorin macrocycles in place of the porphyrin building blocks. Model studies of this type will lead to an understanding of protein control of reactivity that is crucial for solving the medical problems associated with tetrapyrrole biochemistry.