Cytochrome P-450 Polymorphism

描述（由申请方提供）：本申请的目的是定义决定人微粒体细胞色素P450酶底物特异性的结构特征。这些蛋白质参与结构多样的药物、环境毒素和致癌物的代谢，并提供对化学损伤的广泛防御。虽然这些酶可以代谢多种化合物，但它们表现出不同的底物特征。等位基因变异可以选择性地改变代谢能力，并限制主要由单个P450代谢的化合物的安全暴露。正磷酸酶之间的物种差异表明，人类P450酶的彻底表征将提供最可靠的手段来预测药物代谢和化学品暴露的风险。兔2C 5的结构表征提供了有关活性位点结构和底物结合时发生的构象变化的见解。将通过X射线衍射研究表征包括2C 9的四个等位基因变体的人2C酶。活性位点体积和拓扑结构对底物选择性、区域和立体特异性、竞争性抑制、催化能力和激活催化的药物-药物相互作用的影响将使用定点诱变和已知底物和抑制剂的类似物组进行检查。将分析高度保守的天冬氨酸残基所起的作用。还将评价P450构象灵活性的程度和底物依赖性，以确定支配底物识别的动态活性位点特征。这些分析将扩展到各种家庭2 P450酶，以开发一个更全面和连贯的图片P450催化。这些信息将为合理的药物设计和风险评估提供实际依据。

DESCRIPTION (provided by applicant): The objective of this application is to define the structural features that determine the substrate specificities of human microsomal cytochrome P450 enzymes. These proteins participate in the metabolism of structurally diverse drugs, environmental toxins and carcinogens, and provide a broad defense against chemical insults. Although these enzymes can metabolize a wide range of compounds, they exhibit distinct substrate profiles. Allelic variation can selectively alter metabolic capacity and limit safe exposure to compounds that are predominantly metabolized by a single P450. Species differences between orthologous enzymes indicate that thorough characterization of the human P450 enzymes will provide the most reliable means for predicting drug metabolism and the risks of chemical exposure. Structural characterization of rabbit 2C5 has provided insights regarding active site architecture and conformational changes that occur with substrate binding. The human 2C enzymes including four allelic variants of 2C9 will be characterized by x-ray diffraction studies. The influence of active site volume and topology on substrate selectivity, regio and stereo-specificity, competitive inhibition, catalytic competence, and drug-drug interactions that activate catalysis will be examined using site directed mutagenesis and panels of analogs for known substrates and inhibitors. The role played by a highly conserved aspartate residue will be analyzed. The extent and substrate dependence of P450 conformational flexibility will also be evaluated to determine dynamic active site characteristics that govern substrate recognition. These analyses will be extended to various family 2 P450 enzymes in order to develop a more comprehensive and coherent picture of P450 catalysis. This information will provide a practical basis for rational drug design and risk assessment.