CHARACTERIZATION OF HUMAN P450S AND THEIR GENES

该项目的长期目标包括：1)开发 方法评估P450在人类中的表达，以确定P450的作用 这些酶在安全的药物治疗和对环境的敏感性- 以癌症和精神障碍等疾病为基础。2)发展 方便的可用于药物的重组人P450系统 发展和致癌研究。基因的表达和催化作用 在肺和肝组织中表达的人P450的活性正在被 直接检查。人类的肺被发现含有几个P450 形式，最丰富的是细胞色素P4B1。CYP2B7和CYP2F1，表达于 人肺，在肝组织中的含量也较低。在肺里 在吸烟者中发现了CYP1A1。在很大程度上与 这些mRNAs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的证据。CYP2D6 P450是 对药物氧化中的一个主要遗传多态负责。一个数字 已通过DNA直接测序鉴定了多个空的CYP2D6等位基因 来自缺乏CYP2D6催化活性的受试者的基因。这些 在高达10%的高加索人中是主要缺陷的原因。两个变种 发现的等位基因CYP2D6C和CYP2D6J存在氨基酸差异 来自野生型的CYP2D6酶，导致较低的催化速率。 在亚洲人中发现CYP2D6J基因非常频繁，因此解释了 这个民族的代谢率较低，因为许多人的新陈代谢 临床使用的药物。已开发出针对大多数缺陷的聚合酶链式反应测试 可用于诊断代谢物缺陷的CYP2D6等位基因。 研究还发现了CYP2C9基因的一种潜在的多态性 它编码一个负责华法林新陈代谢的P450。几个 人的P450已经被表达成具有催化活性的酶 杆状病毒和牛痘病毒。在Long上发现了一个P450基因位点 19号染色体的臂被克隆在一个超过275kbp的连续片段上。 细胞色素P450基因在细胞色素P450、细胞色素P450 B和细胞色素P450基因亚家族中的定位 通过限制图谱和Southern blotting，这些目前 完全被测序了。

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.