CYTOCHROME P-450 POLYMORPHISM

人细胞色素P450 2C19基因表达的遗传缺陷 根据种族的不同，大约5%-20%的人会出现2D6 背景资料。这种缺陷可能会导致能力减弱 代谢药物和其他外来化合物导致不良副作用- 效果。更多证据表明，这些基因的等位基因变异 和相关的酶可以选择性地影响药物的代谢， 人类其他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。 由于有关活动和表达的信息有限 由这些酶代谢的底物的光谱。要实现更多 人类2C和2D P450的详细特征，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特性。 属性，并生成特定的抗体来表征 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定的抗肽抗体 并确定了2C酶的拓扑特征。后者将是 与基于可溶性原核生物P450结构的模型进行比较。 基于经验的定点突变方法将是 被用来绘制人类催化特异性的决定因素 2C和2D酶，并改进其活性的基于计算机的模型 底物的位点和基于药效团的模型 专一性。将努力使哺乳动物的微粒体晶化 用于X射线衍射研究的P450，使用的是 这些酶在保持其催化性能的同时可溶。

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.