摘要
为探讨中国人S-美芬妥英/奥美拉唑氧化代谢多态性的分子机制,本文用多聚酶链式反应(PCR)方法扩增出CYP2C19intron4/exon5特异的DNA片段,并用限制性内切酶SmaI进行酶切分析。研究结果表明,16位健康志愿者(9名S-MPEMs,7名S-MPPMs)的CYP2C19存在SmaI酶切位点的多态性,且与S-MP羟化代谢表型有相关性。在9名EMs中,有3名为CYP2C19wt/wt的纯合子,而在7名PMs中,有4名为CYP2C19m/m的纯合子,余下9位均为杂合子(CYP2C19wt/m)。因此中国人导致S-MP弱代谢表型主要由于CYP2C19基因外显子5的SmaI酶切位点的突变。但这种突变只能解释S-MPPMs的80%等位基因突变(CYP2C19m)或60%的中国受试者弱代谢表型。对中国人CYP2C19基因intron4/exon5DNA序列进行测定的结果表明,在EMs的基因序列中有一个SmaI酶位切点,而在PMs中,由于G→A突变,使SmaI酶位切点消失。
It is well known now that the hydroxylative metabolism of S-MP is catalized by cytochrome P450 2C19(CYP 2C19). For genotyping analysis, DNA was isolated from the blood of 16 Chinese normal subjects who had been previously phenotyped(9 were S-MP EMs and 7 were S-MPPMs). Then the specific DNA fragment of CYP 2C19 was amplified by technique of PCR and digested with restrictive endoclease Sma I.000 Our results demonstrated that among the 16 subjects,4 were homozygous for the wild-type gene(CYP 2C19 wt/wt), 4 of them were homozygous for mutant gene(CYP 2C19 m/m)and 9 others were heterozygous(CYP 2C19 wt/m). Thus, the CYP 2C19m defect accounted for 11 of 14 alleles(80%)in Chinese poor metabolizers and could explain about 60% PMs phenotypes. This defect was not able to explain all PMs.It is therefore indicated the existence of another, yet unidentified mutation. DNA from two individuals, including 1 homozygous EMs and 1 hormozygous PMs was amplifled, subcloned into pGEM-T vector and sequenced.Our results indicated that only CYP 2C19 intron4/exon5 was amplified in the genotyping test. The principal defect in poor metabolizer is a single base pair(G→A)mutation in exon5 of CYP2C19, which created an aberrant splicing site and resulted in a non-functional enzyme protein, but the nucleotide sequence of intron 4 of the mutated gene is identical to that of the normal gene.
出处
《中国临床药理学杂志》
CAS
CSCD
北大核心
1996年第1期13-19,共7页
The Chinese Journal of Clinical Pharmacology
基金
国家自然科学基金
关键词
S-美芬妥英
奥美拉唑
羟化代谢
多态性
S-mephenytoin
omeprazole
oxidative polymorphism
geuetic variation
molecular basis