DRUG METABOLIZING ENZYMES IN HUMANS AND ANIMAL MODELS

工作总结：CYP酶代谢药物和外源物质，以及 这些酶中的一些酶的多态解释了 人类的新陈代谢。我们已经确定了CYP2C19的五个缺陷 对抗惊厥药物的代谢物不良负责 美苯妥因和抗溃疡药物奥美拉唑并开发了基因测试 这些多态中的两个。基因测试是在我们的 实验室确认了大约100%的东方人和大约96%的高加索人经前综合症 在临床研究中。某些穷人的起始密码子突变 代谢剂可以防止翻译。血红素结合中的一种新突变 已经确定了阻止另一种蛋白质在 C DNA表达系统。鉴定出外显子3的氨基酸突变。 在美苯妥因的不良代谢物中，并在cDNA3中表达 表达系统来验证它是否是有缺陷的等位基因。 更多的研究旨在找出更多的缺陷 发展和提高基因检测的准确性。一个 CYP2C9缺陷等位基因影响其与底物的亲和力 降糖药物甲苯丁胺和抗癌药物 环磷酰胺对甲苯磺丁胺和华法林代谢的影响 活着。细胞色素P450酶C基因的cDNAs测序鉴定出4个新的细胞色素P2酶C 小鼠，一种常见的毒性和致癌性实验动物 测试。这些小鼠的P450在cDNAs表达系统中表达 以及它们在药物代谢和内源性化合物等方面的比较 因为花生四烯酸正被与人类形式进行比较。一个 一种新的犬类细胞色素P450 2 C被鉴定为多态 可能是某些化合物代谢变化的原因 在狗身上，一种常见的实验室用药实验动物。C DNA的表达 定点突变研究正被用来识别氨基 在底物专一性中起重要作用的酸 亚家族。人细胞色素P450酶C的构效关系研究已确定 SRS 2和4区域在奥美拉唑、华法林、 一种抗凝剂，以及一种抗炎药双氯芬酸。研究是 目的是识别人类P450中的关键氨基酸， 授予特定药物和环境化学品的专属性。 CDNAs的表达研究旨在确定哪种细胞色素P450 2 C 酶参与了农药的代谢，而农药的新陈代谢 花生四烯酸等底物。这类研究也在尝试 共同确定P450模型中与自杀有关的区域 底物如替尼罗酸的活化和形成 人类的自身免疫抗体。这些研究将有助于确定哪些是 P450分子的一部分具有高度的特异性和 对某些药物和外源物质的选择性，以及模型将有所帮助 预测哪些附加化合物将被这些P450代谢 酵素。

Summary of Work: The CYP enzymes metabolize drugs and xenobiotics, and polymorphism in some of these enzymes accounts for variability in metabolism in man. We have identified five defects in CYP2C19 responsible for poor metabolizers (PMS) of the anticonvulsant drug mephenytoin and the antiulcer drug omeprazole and developed genetic tests for two of these polymorphisms. Genetic tests developed in our laboratory identify about 100% of Oriental and about 96% of Caucasian PMS in clinical studies. A mutation in the initiation codon of certain poor metabolizers prevents translation. A new mutation in the heme binding region has been identified which prevents expression oth eh protein in a cDNA expression system. An amino acid mutation in exon 3 was identified in a poor metabolizer of mephenytoin and is being expressed in cDNA expression systems to verify whether it is a defective allele. Additional studies are directed toward identifying additional defects in CYP2C19 and developing and improving the accuracy of genetic testing. A defective allele of CYP2C9 affects its affinity for substrates such as the antidiabetic drug tolbutamide and the anticancer drug cyclophosphamide and affects metabolism of tolbutamide and warfarin in vivo. Sequencing of cDNAs of CYP2Cs have identified four new CYP2Cs in the mouse, a common laboratory animal for toxicity and carcinogenicity tests. These mouse P450s are being expressed in cDNA expression systems and their comparison of metabolism of drugs and endogenous compounds such as arachidonic acid is being compared with that of the human forms. A new canine CYP2C was identified which has been shown to be polymorphic and may be responsible for variability in metabolism of certain compounds in the dog, a common laboratory test animal for drugs. cDNA expression and site-directed mutagenesis studies are being used to identify amino acids which are important in the substrate specificity oof the CYP2C subfamily. Structure-activity studies of human CYP2Cs have identified areas in SRS 2 and 4 as important in metabolism of omeprazole, warfarin, an anticoagulant, and diclofenac, an anti-inflammatory drug. Studies are directed toward identifying key amino acids in the human P450s which confer specificity for particular drugs and environmental chemicals. cDNA expression studies are directed toward identifying which CYP2C enzymes are involved in pesticide metabolism, and metabolism of the arachidonic acid and other substrates. Such studies are also attempting collaboratively to identify regions of the P450 model involved in suicide activation of substrates such as tienilic acid and the formation of autoimmune antibodies in humans. These studies will help identify which portions of the P450 molecule permit their high degree of specificity and selectivity toward certain drugs and xenobiotics, and models will help predict which addtional compounds will be metabolized by these P450 enzymes.