STRUCTURE FUNCTION OF CYTOCHROME P450

细胞色素 P450 的结构功能

• 批准号: 6100796
• 负责人: F K FRIEDMAN
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6100796
• 关键词: carbon monoxide; chemical binding; chemical carcinogen; chemical models; computer simulation; cytochrome P450; enzyme activity; enzyme induction /repression; enzyme inhibitors; enzyme structure; enzyme substrate complex; human tissue; laboratory rat; membrane lipids; microsomes; protein structure function; toxicant interaction

The cytochrome P450s oxidize a wide variety of xenobiotic and endogenous compounds. Biochemical, biophysical and computational approaches were applied to examine the structure-function relationships which govern the interactions of P450s with substrates, membrane lipids and microsomal proteins. The CO binding kinetics was used as a probe of P450 conformation and dynamics, to define the effect of various drugs and carcinogens on P450s. Of particular interest is the finding that both human P450 1A1, which metabolizes carcinogens, and P450 3A4, which metabolizes a variety of important drugs, are composed of multiple conformers with distinct substrate specificities. This finding was used to elucidate 7,8-naphthoflavone activation of P450 3A4 and inhibition of P450 1A1, and the mechanism of quinidine inhibition of P450 3A4 mediated nifedipine metabolism. In addition, CO binding kinetics was applied to examine the differential binding of erythromycin to rat P450s 3A1 and 3A2, which exhibit 89% sequence similarity. The results indicate a model of the P450 substrate binding site in which erythromycin forms a more rigid complex with P450 3A1 than P450 3A2. These results show that CO binding kinetics can distinguish among closely related P450s in the same microsomal membrane. We employed molecular modeling to generate a P450 2B1 model. P450 recognition surfaces for NADPH cytochrome P450 reductase were predicted, and the corresponding peptides were prepared and assessed for their ability to inhibit the P450-reductase interaction. The most potent peptide inhibitors were topographically derived from spatially proximate P450 sequences in the C and L-helices and the meander region. The model also suggests a membrane binding domain which consists of the amino terminal region, the pre-A helix region and the F-G loop. In addition, when several known substrates were docked into the substrate binding site, the observed substrate-P450 interactions were consistent with the known substrate specificity of P450 2B1. This model thus suggests reductase, membrane and substrate binding domains of this P450.

细胞色素P450氧化多种异生物质和内源性 化合物.生物化学、生物物理和计算方法， 应用于检查结构功能关系，支配 P450与底物、膜脂和微粒体的相互作用 proteins. CO结合动力学被用作P450探针 构象和动力学，以确定各种药物的作用， P450上的致癌物质特别令人感兴趣的是， 人P450 1A 1，其代谢致癌物，和P450 3A 4， 代谢多种重要药物，由多种 具有不同底物特异性的构象。这一发现被用于 阐明7，8-萘醌对P450 3A 4的激活和抑制作用 奎尼丁抑制P450 3A 4的机制 介导硝苯地平代谢。此外，CO结合动力学是 应用于检测红霉素与大鼠P450 s的差异结合 3A 1和3A 2，它们表现出89%的序列相似性。结果表明 P450底物结合位点的模型，其中红霉素形成 与P450 3A 1的复合物比与P450 3A 2的复合物更刚性。这些结果表明 CO结合动力学可以区分密切相关的P450， 相同的微粒体膜。 我们采用分子建模来生成P450 2B 1模型。P450 预测了NADPH细胞色素P450还原酶的识别表面， 并制备相应的肽并评估其 抑制P450-还原酶相互作用的能力。最有效的 肽抑制剂是从空间上接近的 在C和L-螺旋和曲流区的P450序列。模型 还提出了一种膜结合结构域， 末端区、前A螺旋区和F-G环。此外，本发明还提供了一种方法， 当几个已知的基底对接到基底结合件中时 位点，观察到的底物-P450相互作用与 已知P450 2B 1的底物特异性。该模型表明， 还原酶，膜和底物结合域的P450。