A Comprehensive Study on the Effects of Genetic Polymorphism on the Drug Metabolizing Activity of Human CYP

在本研究中，我们专注于细胞色素P450（CYP450），这是人类药物代谢酶的优势群体，我们的目的是建立一个临床原则，适用于订单治疗，通过全面研究的药物结合和代谢活性的突变体，这是根据人类基因组单核苷酸多态性（SNPs）的信息制备的基础上。我们利用已经建立的CYP2C9过表达系统，制备了基于SNP信息的CYP2C9和CYP2C19突变体。我们用微透析法测定了野生型和突变型CYP的药物结合活性。通过HPLC测定结合药物的量，我们发现经CYP2C9代谢的双氯芬酸和华法林对CYP2C9显示出预期的高亲和力。然而，也发现硝苯地平（被认为是由CYP3A4代谢的）对CYP2C9的亲和力高于双氯芬酸。此外，地西泮被假定为经CYP2C19代谢，但与CYP2C19相比，地西泮与CYP2C9的亲和力相对较高。这些结果强烈表明，我们必须重新考虑药物相互作用的特异性。我们进一步研究了SNP突变体的药物结合亲和力，我们发现所有突变体的亲和力都降低。提示对有SNP突变的患者应减少用药剂量。我们还完成了CYP1A2、CYP2D6和CYP3A4的克隆，并建立了这些蛋白的纯化程序。

In this study, we focused on cytochrome P450(CYP) which is a dominant group in the human drug metabolizing enzymes, and we aimed at the establishment of a clinical principle which is applicable to order-made treatment, through comprehensive studies on the drug binding and metabolizing activities of mutants which are prepared on the bases of the information of human genomic single-nucleotide polymorphisms(SNPs). We used over-expression system of CYP2C9 which is already established by us, and prepared CYP2C9 and CYP2C19 mutants on the SNP information. We measured drug binding activities of the wild-type and mutant CYPs by micro-dialysis method. The amount of bound drugs was determined by HPLC and we found that diclofenac and warfarin, which are metabolized by CYP2C9, show high affinity to CYP2C9 as expected. However, it was also found that nifedipine, which has been supposed to be metabolized by CYP3A4, show higher affinity to CYP2C9 than diclofenac. In addition, diazepam has been assumed to be metabolized by CYP2C19, but it showed relatively higher affinity to CYP2C9 than that to CYP2C19. These results strongly suggest that we must re-consider the specificities of drug-CYP interactions. We further studied the drug binding affinities to SNP mutants, and we found that the affinity decreases in all of the mutants. This suggests that we should decrease administration doze to the patients who have SNP mutation. We also completed the cloning of CYP1A2,CYP2D6, and CYP3A4, and established the purification procedure of these proteins.