MOLECULAR PROBES OF THE MECHANISM OF CYTOCHROME P-450

肺、肝、肾和上皮组织中的细胞色素P-450 已知在致癌物激活、药物和外源生物中发挥核心作用 解毒、类固醇和前列腺素代谢。这样做的目的是 程序是为了阐明有机和无机化学的 由细胞色素P-450介导的过程统称为氧- 激活和底物氧化。我们的双管齐下的方法是 (I)使用细胞色素P-450的底物，旨在揭示其性质 看不见的中间体和(Ii)开发模型系统作为化学物质 这些过程的范例。这些研究的一个重要方面是 直接比较了酶反应和模型反应中的相同 实验室。下一批赠款期间拟开展的具体活动如下： 1.含氧铁卟啉的结构和反应活性 含氧铁卟啉配合物的结构和相互转化 继续深入了解化学事件的性质 称为氧活化。我们计划制备过氧化氢铁(III) 卟啉络合物及相关含氧物种的研究 向氧铁(IV)卟啉阳离子等活性络合物的转化 激进分子。我们还将探讨为编制类似的 与生物相关的亚铁血红素硫酸盐连接的络合物 铁制的。 2.重组膜中的P-450模型。 我们计划使用合成和半合成磷脂组件来 模拟和理解P-450作用中的电子转移事件 膜环境。具体来说，我们将：(1)设计模型膜- 可以促进对难以捉摸的铁(III)的研究的卟啉体系- 硫代配位环境；(2)探索区分的方法 膜结合卟啉及其相关氧化还原的空间取向 组件有助于理解一般的向量过程；(3) 探索我们最新的发现，膜结合的氧化还原酶，如 细胞色素P-450还原酶、细胞色素b5和丙酮酸氧化酶可以 与合成膜氧化还原伙伴进行有效沟通。 3.以DNA为底物；双链和单链的选择性反应； 搁浅的DNA。 我们计划设计水溶性金属卟啉和相关的非卟啉 金属络合物和探索选择性DNA和RNA链切割 这些物种。这一努力可能会产生选择性的试剂， 寡核苷酸的氧化切割，可能为新的 基于氧金属的抗肿瘤和抗病毒化合物家族 细胞色素P-450的化学。我们还计划研究DNA裂解 阳离子卟啉衍生物与两种金属配位的反应 并探讨该物种与铁蛋白基因的相互作用。

The cytochrome P-450 of lung, liver, kidney, and epithelial tissue are known to play a central role in carcinogen activation, drug and xenobiotic detoxification and steroid and prostaglandin metabolism. The goals of this program are to elucidate the organic and inorganic chemistry of the processes mediated by cytochrome P-450 referred to collectively as oxygen- activation and substrate oxygenation. Our two-pronged approach has been (i) to employ substrates for cytochrome P-450 designed to reveal the nature of unseen intermediates and (ii) to develop model systems as chemical paradigms for these processes. An important aspect of these studies has been the direct comparison of enzymic and model reactions in the same laboratory. Specific activities proposed for the next grant period are: 1. Structure and Reactivity of Oxygenated Iron Porphyrins. The structure and interconversions of oxygenated iron porphyrin complexes continue to afford insight regarding the nature of the chemical events referred to as oxygen activation. We plan to prepare hydroperoxoiron(III) porphyrin complexes and related oxygenated species and observe their conversion to reactive complexes such as oxoiron(IV) porphyrin cation radicals. We will also explore strategies for the preparation of similar complexes with the biologically relevant thiolate ligation of the heme iron. 2. P-450 MOdels in Reconstituted Membranes. We plan to use synthetic and semi-synthetic phospholipid assemblies to model and understand the electron transfer events on P-450 action in membrane environments. Specifically, we will: (1) devise model membrane- porphyrin systems which can facilitate the study of the elusive iron(III)- thiolate coordination environment; (2) explore methods of differentiating the spatial orientation of membrane bound porphyrins and related redox components toward an understanding of vectorial processes in general; (3) explore our very recent finding that membrane bound redox enzymes such as cytochrome P-450 reductase, cytochrome b5, and pyruvate oxidase can communicate effectively with synthetic membrane redox partners. 3. DNA as a Substrate; Selective Reactions of Double-Stranded and Single- Stranded DNA. We plan to design water-soluble metalloporphyrins and related non-porphyrin metal complexes and to explore selective DNA and RNA strand cutting with these species. The effort may result in reagents for the selective, oxidative cleavage of oligonucleotides and may provide the basis for new families of antitumor and antiviral compounds based on the oxometal chemistry of cytochrome P-450. We plan also to study the DNA cleavage reactions of derivatives of cationic porphyrins with two metal coordinating appendages and to explore interactions of the species with ferritin mRNA.