DRUG METABOLIZING ENZYMES IN HUMANS AND ANIMAL MODELS

工作总结：代谢酶代谢药物和外源性物质， 这些酶中的一些的多态性解释了 我们已经确定了CYP 2C 19的五个缺陷， 负责抗惊厥药物的弱代谢型（PMS） 美芬妥英和抗溃疡药物奥美拉唑，并开发了基因测试 其中两个多态性。 基因测试在我们的 实验室鉴定出大约100%东方人和大约96%的高加索人PMS 在临床研究中。 在某些穷人的起始密码子突变 代谢者阻止翻译。 血红素结合的新突变 已经鉴定了一个区域，它阻止了其他蛋白在细胞中的表达。 cDNA表达系统。 在外显子3上发现一个氨基酸突变 在美芬妥英的弱代谢者中， 表达系统来验证它是否是缺陷等位基因。 进一步的研究是针对确定其他缺陷， CYP 2C 19和开发和提高基因检测的准确性。 一 CYP 2C 9的缺陷等位基因影响其对底物的亲和力， 抗糖尿病药物甲苯磺丁脲和抗癌药物 环磷酰胺和影响代谢的甲苯磺丁脲和华法林， vivo. 对CYP 2C基因的cDNA进行测序，发现了4个新的CYP 2C基因， 小鼠，一种常见的毒性和致癌性实验动物 试验. 这些小鼠P450在cDNA表达系统中表达， 以及药物和内源性化合物代谢的比较， 因为花生四烯酸被拿来和人类的身体相比较。 一 发现了一种新的犬CYP 2C，它具有多态性 并可能导致某些化合物代谢的变化 在狗身上，一种常见的药物实验室试验动物。 cDNA表达 定点突变研究被用来鉴定氨基 对CYP 2C底物特异性重要的酸 亚科 人CYP 2C的结构-活性研究已经确定 SRS 2和4中的区域在奥美拉唑、华法林 一种抗凝血剂和双氯芬酸一种抗炎药 研究是 旨在鉴定人类P450中的关键氨基酸， 赋予特定药物和环境化学品的特异性。 cDNA表达研究旨在确定哪种CYP 2C 酶参与农药代谢， 花生四烯酸和其它底物。这些研究也试图 协同识别参与自杀的P450模型区域 底物如噻吩甲酸的活化和 自身免疫抗体 这些研究将有助于确定 P450分子的部分允许它们的高度特异性， 对某些药物和外源性物质的选择性，以及模型将有助于 预测哪些化合物将被这些P450代谢 内切酶

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.