CYTOCHROME P-450 POLYMORPHISM

人类细胞色素P450 2C 19或 根据种族，2D 6分别发生在大约5-20%的个体中 背景 这些缺陷可能导致能力下降， 代谢药物和其他外来化合物，导致不良副作用， 方面的影响.其他证据表明，这些等位酶变异 和相关酶可以选择性地影响药物代谢， 其他人类2C酶表达的个体间差异 也会发生。很难预测这些变化的影响 活动和言论自由的信息有限， 这些酶代谢底物的光谱。能够更 详细描述人类2C和2D P450，我们正在开发 在大肠杆菌中高水平表达这些酶的方法。 这些酶的制备将用于表征酶的性质。 特性，并产生特异性抗体来表征 人P450 2C酶的表达。从表位收集的信息 图谱研究将用于产生特异性抗肽抗体 并定义2C酶的拓扑特征。后者将 与基于可溶性原核P450结构的模型相比。 基于经验的定点突变方法将是 用于绘制人的催化特异性的决定因素， 2C和2D酶，并完善其活性的基于计算机的模型 位点以及基于药效团的底物模型 的特异性将努力使哺乳动物微粒体结晶 P450用于X射线衍射研究， 这些酶是可溶的，同时保持它们的催化性质。

Genetic deficiencies in the expression of human cytochromes P450 2C19 or 2D6 each occur in roughly 5-20% of individuals depending on racial background. Such deficiencies can lead to diminished capacities to metabolize drugs and other foreign compounds leading to undesirable side- effects. Additional evidence suggests that allozymic variation for these and related enzymes can selectively affect drug metabolism and that inter-individual variation in the expression of other human 2C enzymes also occurs. It is difficult to predict the affects of these alterations of activity and expression due to limited information regarding the spectrum of substrates metabolized by these enzymes. To enable a more detailed characterization of the human 2C and 2D P450s, we are developing means for the high-level expression of these enzymes in Escherichia coli. Preparations of these enzymes will be used to characterize the enzymic properties and to generate specific antibodies to characterize the expression of the human P450 2C enzymes. Information gleaned from epitope mapping studies will be used to generate specific anti-peptide antibodies and to define topological features of the 2C enzymes. The latter will be compared to models based on the structures of soluble prokaryotic P450s. Empirically based approaches to site-directed mutagenesis will be employed to map determinants of the catalytic specificities of the human 2C and 2D enzymes and to refine computer based models for their active sites as well as pharmacophore based models for their substrate specificity. Efforts will be made to crystallize the mammalian microsomal P450s for X-ray diffraction studies utilizing modifications that render the enzymes soluble while retaining their catalytic properties.