SYNTHETIC PROBES OF HEME AND CHLOROPHYLL BIOCHEMISTRY

我们计划使用综合模型方法通过以下方式来探索这些机制 自然界控制和改变了亚铁血红素的化学成分 叶绿素。我们将专注于当前兴趣浓厚的两个领域， 光合作用反应中心和细胞色素P-450。一种新的方法是 用于制备共价堆积的卟啉衍生物的建议 这将作为反应中心的准确模型。使用新的 合成对称的卟啉前驱体我们将制备二聚体、三聚体 以及不同几何结构、组成和金属状态的低聚物。 对这些分子的详细物理和光谱分析将 提供对叶绿素几何排列的洞察 光合作用。我们还提议合成 叶绿素二聚体-叶绿素供体-受体复合体的研究 第一阶段控制正反向电子转移的因素 光合作用电荷分离步骤。 我们的第二个研究主题涉及对 底物结合部位和活性部位的远端蛋白基团 重要的单加氧酶，细胞色素P-450。我们已经准备了一份 含有合成底物结合的一系列分子受体 与一种卟啉非常接近的地点。这些新物种应该 准确地对酶-底物复合体进行建模，使我们能够研究 详细阐述了分子机制。各种远端组将被合并 进入分子受体及其对血红素化学的影响 被监视着。受体也显示出相当大的前景作为催化剂 烷烃羟化和烯烃环氧化。它的类酶特性 底物选择性和反应区域专一性原则上应为 由结合部位的精心设计控制。

We plan to use the synthetic model approach to probe the mechanisms by which nature controls and modifies the chemistries of the hemes and chlorophylls. We will concentrate on two areas of strong current interest, the photosynthetic reaction centers and cytochrome P-450. A new method is proposed for the preparation of covalently stacked porphyrin derivatives which will serve as accurate models for reaction centers. Using a newly synthesized symmetrical porphyrin precursor we will prepare dimers, trimers and oligomers of varying geometries, compositions and metallation states. Detailed physical and spectroscopic analysis of these molecules will provide insights into the geometrical arrangement of chlorophylls in photosynthesis. We are also proposing to synthesize models of the chlorophyll dimer - pheophytin donor-acceptor complex in order to probe the factors which control forward and reverse electron transfer in the first photosynthetic charge separation step. Our second research theme involves a study of the role of the substrate-binding site and distal protein groups on the active site of the important monooxygenase enzyme, cytochrome P-450. We have prepared a series of molecular receptors which contain a synthetic substrate binding site in close proximity to a porphyrin. These novel species should accurately model the enzyme-substrate complex and allow us to study the molecular mechanism in detail. Various distal groups will be incorporated into the molecular receptor and their influence of heme chemistry will be monitored. The receptors also show considerable promise as catalysts for alkane hydroxylation and alkene epoxidation. The enzyme-like properties of substrate selectivity and reaction regiospecificity should in principle be controlled by careful design of the binding site.