CHARACTERIZATION OF HUMAN P450S AND THEIR GENES

该项目的长期目标包括：1）开发 评估人类P450表达的方法，以确定 这些酶在安全的药物治疗和环境敏感性， 癌症和精神疾病等基础疾病。 2)发展 可用于药物治疗的方便的基于重组人P450的系统 发展和致癌研究。 表达和催化 在肺和肝组织中表达的人P450的活性正在被 直接检查。 人肺中发现含有几种P450 最常见的是CYP4B1。 CYP2B7和CYP2F1，表达于 在肝组织中也发现了较低水平的人肺。 肺中 从吸烟者，CYP1A1被发现。 这些mRNA水平的个体差异被发现，但没有明确的 从这些数据中出现了多态性的证据。CYP2D6 P450 负责药物氧化的主要遗传多态性。 一些 的无效CYP2D6等位基因已通过直接DNA测序进行了表征 来自缺乏CYP2D6催化活性的受试者的基因。 这些 占白种人的10%。 两个变体 发现CYP2D6C和CYP2D6J等位基因具有氨基酸差异 从野生型CYP2D6酶，导致较低的催化速率。 发现CYP2D6J在亚洲人中非常常见，因此解释了 这个种族的新陈代谢速度较慢， 临床使用的药物。PCR检测已开发用于大多数缺陷 CYP2D6等位基因可用于诊断代谢缺陷型。 研究还揭示了CYP2C9基因的潜在多态性 编码一个负责代谢华法林的P450 几 人P450已被表达成催化活性酶， 杆状病毒和牛痘病毒。P450基因的一个位点在长 19号染色体的臂克隆在超过275kbp的连续片段上。 对CYP2A、CYP2B和CYP2F基因亚家族中的P450基因进行定位 通过限制性酶切图谱和Southern印迹，这些是目前 被完全排序。

The long-term goals of this project include: 1) The development of methods to assess P450 expression in humans to determine the roles of these enzymes in safe drug therapy and susceptibility to environmentally- based diseases such as cancer and mental disorders. 2) To develop convenient recombinant human P450-based systems that can be used in drug development and carcinogenesis research. The expression and catalytic activities of human P450s expressed in lung and liver tissues are being directly examined. The human lung was found to contain several P450 forms, the most abundant being CYP4B1. CYP2B7 and CYP2F1, expressed in human lung, are also found at lower levels in liver tissue. In lungs from tobacco smokers, CYP1A1 is found. A large degree of inter- individual variability in levels of these mRNAs were found, but no clear evidence for a polymorphism emerged from these data. The CYP2D6 P450 is responsible for a major genetic polymorphism in drug oxidation. A number of null CYP2D6 alleles have been characterized by direct DNA sequencing of genes from subjects deficient in CYP2D6 catalytic activities. These account for the primary defect in up to 10% of Caucasians. Two variant alleles, CYP2D6C and CYP2D6J, were found that have amino acid differences from the wild-type CYP2D6 enzyme, resulting in lower catalytic rates. CYP2D6J was found to be very frequent in Asians, thus accounting for the slower metabolic rates of this ethnic group for metabolism of many clinically used drugs. PCR tests have been developed for most defective CYP2D6 alleles that can be used to diagnose deficient metabolizers. Studies have also revealed a potential polymorphism in the CYP2C9 gene that encodes a P450 responsible for metabolism for warfarin. Several human P450s have been expressed into catalytically-active enzymes using baculovirus and vaccinia virus. A locus of P450 genes found on the long arm of chromosome 19 were cloned on a contiguous segment of over 275 kbp. P450 genes in the CYP2A, CYP2B, and CYP2F gene subfamilies were localized by restriction mapping and Southern blotting and these are currently being completely sequenced.