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这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 (1)真核细胞色素P450(P450)是普遍存在的一种完整的膜酶，能催化大量外源和内源化合物的单氧合作用。这些反应包括清除环境毒素和致癌物的途径，合成类固醇、类固醇和前列腺素的途径，在某些情况下，还包括化学致癌物的代谢激活。大量的实验室研究微粒体P450，并将从结构模型中受益匪浅。我们建议1)继续对哺乳动物P450进行更高分辨率的结晶学研究，以进一步表征膜|附着表面，2)确定当底物结合和络合物减少时蛋白质结构发生了什么变化，以及3)将结晶方法扩展到具有药理意义的相关微粒体P450。这些研究中将要确定的结构将解决蛋白质与膜的相互作用以及底物结合和识别的问题。此外，这些研究将产生关于膜结合模式的重要新信息，并可能有助于推进用于结构研究的膜蛋白工程背后的方法学。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. (1) Eukaryotic cytochromes P450 (P450s) are ubiquitous, integral membrane enzymes that catalyze the mono-oxygenation of a large number of both exogenous and endogenous compounds. These reactions include pathways for the purging of environmental toxins and carcinogens, the synthesis of sterols, steroids and prostanoids and, in some cases, the metabolic activation of chemical carcinogens. A large number of laboratories study microsomal P450s and will benefit greatly from a structural model. We propose 1) to continue crystallographic studies of mammalian P450s to higher resolution in order to further characterize the membrane |attachment surface, 2) to determine what changes occur in the structure of the protein when substrate binds and the complex is reduced, and 3) to extend the crystallization methodology to related microsomal P450s of pharmacological interest. The structures to be determined in these studies will address questions about the interaction of the protein with the membrane as well as substrate binding and recognition. In addition, these studies will yield significant new information regarding modes of membrane binding, and may help to advance the methodology behind the engineering of membrane proteins for structural studies.