中国苗族人群中细胞色素P450 2C19基因多态性的研究

为研究细胞色素P45 0 2C19在中国苗族人群中的基因型 ,采用聚合酶链式反应与限制性内切核酸酶片段长度多态性技术分析了 98例无血缘关系苗族人群的基因型。结果显示 5 0人为CYP2C19野生型纯合子 (wt/wt) ;39人为CYP2C19m1杂合子 (wt/m1) ;9人为CYP2C19m1突变型纯合子 (m1/m1)。与国内外相关报道比较 ,本实验得出的CYP2C19m1突变频率与文献报道相符     

104名藏族志愿者中细胞色素P450 2C19m1的基因多态性

细胞色素P450 2C19（CYP2C19）参与临床上许多重要药物的代谢。根据其代谢S－美芬妥英或其他CYP2C19底物的能力不同,有强代谢者（EMs）和弱代谢者（PMs）之分。PMs表型的频发率存在明显的种族差异。在本文中,我们主要报道了细胞色素P450 2C19 m1在中国藏族人群中的多态性分布。在104例无血缘关系藏族人群中,49人（47.1%）为CYP2C19野生型纯合子（wt/wt）,46人（44.2%）为CYP2C19m1杂合子（wt/m1）,9人（8.7%）为CYP2C19m1突变型纯合子（m1/m1）。CYP2C19野生型等位基因频率为0.692,CYP2C19m1等位基因频率为0.308。该结果与国内外报道的中国其余民族的CYP2C19m1等位基因频率相比具有一定可比性。 关键词：细胞色素P450 2C19;基因型;藏族;聚合酶链反应;限制性内切核酸酶片段长度多态（RFLP）Abstract: Cytochrome P 450 2C19（CYP2C19） is involved in the metabolism of a number of clinically used drugs. Individuals can be characterized as extensive metabolizers （EMs）or poor metabolizers（PMs）, according to the drugs-metabolized ability of CYP2C19 in population studies. The incidence of poor metabolizer phenotype shows marked interracial differences. In this article we report the gene polymorphism of CYP2C19 in Zang population. There were 49 wild-type homozygotes（wt/wt）, 46 were heterozygotes（wt/m1） and 9 were homozygotes（m1/m1） among 104 unrelated Zang subjects. The frequency of CYP2C19m1 allele was 0.308, which was in agreement with that in other published data.     

昆虫细胞色素P450研究:P450基因

细胞色素P450广泛存在于生物界,它因参与许多外来物质和内源性物质的代谢而具有十分重要的作用［1－5］细胞色素P450的研究大约有50多年的历史[3]。60年代的工作主要是对这一血红素蛋白的生物化学和生物物理学特征的了解以及膜结合P450酶系的酶学功能[3]。70年代的研究集中在细胞色素P450酶系的分离纯化及其活性的重组。纯化P450的成功证明了许多P450在物理学和酶学特征方面的不同,也为制备抗体及利用抗体来确定某种P450的存在与数量以及抑制特定P450的酶活性提供了手段,使进一步阐明P450的反应机制成为可能。80年代分子生物学技术的…     

昆虫细胞色素P450的研究:P450基因的进化

80年代分子生物学方法被用于分离和鉴定特定P450的CDNA或基因组克隆［‘］,至今已知的P450基因包括70个基因家族、127个亚家族的40O多个,基因序列的数量还在迅速增加I’］。不同P450间的进化关系在一些综述中都有涉及［”’,‘］,本文介绍这一主题的一些主要观点,重点放在P450功能的进化及其机制。亚细胞色素P450的基本特征及其分类与命名所有细胞色素P450具有一非共价结合的血红素和环绕高度保守的半跳氨酸的一段26氨基残基的保守序列,这一半跳氨酸提供血红素铁的第5个配体（ligand）。当血红素铁接受电子被还原后再与CO结合产…     

细胞色素P450基因及其在植物改良中的应用

细胞色素P450是一类含血红素的氧化还原酶类,它参与多种生化反应,在防御生物免受病虫害及逆境胁迫等方面具有重要作用。生物基因组序列分析表明,它是一个基因超家族。许多细胞色素P450基因已被鉴定和克隆,并应用于植物遗传改良;在转基因培育多抗性植物、创造植物雄性不育系,提高植物降解化学农药残留等污染物的能力和有效生产具有药用价值的化合物等方面已取得可喜进展,显示出广阔的应用前景。 Abstract:Cytochrome P450s are heme-containing mixed-function oxidases,involving in lots of biochemical reactions.They play an important role in preventing plants from pathogen and insect attacks and environmental stress.Sequence analysis of genomes has revealed that P450 is a gene super-family.Many cytochrome P450s have been characterized and cloned.Some of them have been used in plant genetic improvement.A great progress has been made in using these P450 genes to create the transgenic plants with multiple resistances,male sterility,higher capability to dissolve toxic chemicals and pollutants and effective productivity of high valuable compounds,indicating P450 genes have a broad prospect with great potential application.     

细胞色素P450的多样性

细胞色素Ｐ４５０的多样性＊邱星辉冷欣夫（中国科学院动物研究所,北京１０００８０）关键词细胞色素Ｐ４５０多样性细胞色素Ｐ４５０是一类以还原态与ＣＯ结合后在波长４５０ｎｍ处有吸收峰的含血红素的单链蛋白质［１～３］。它于１９５８年被发现以来,就引起了人们的...     

淡色库蚊细胞色素P450基因研究

采用一对昆虫细胞色素P450简并引物,以反转录-聚合酶链反应从淡色库蚊对溴氰菊酯敏感品系和抗性品系成虫RNA扩增到约485 bp和510 bp两个片段,将这两个片段与PinPoint^TMXa-1 T质粒重组,然后克隆至大肠杆菌JM109菌株,筛选获得68个阳性克隆;其中24个阳性克隆测序后与GenBank资料对照,显示为细胞色素P450新序列;分子系统学研究显示,24个新基因（等位基因）分别属CYP4家族CYP4C、CYP4D、CYP4H和CYP4J等4个亚家族,其已由细胞色素P450命名委员会命名和GenBank登录上网;其中CYP4C23可能是一个假基因,CYP4H13具有一段58个碱基长度的内含子,CYP4J4V1在近3′端具有一个终止密码子TAG.     

CYP2C19遗传多态性的研究进展

S-美芬妥英羟化代谢多态性不仅存在个体差异,而且存在种族差异。CYP2C19基因是决定S-美芬妥英羟化代谢的决定基因,该基因的突变是导致S-美芬妥英羟化代谢多态性的分子机制。近年来对CYN50s基因型和表型相关性的研究越来越受到重视,人们希望利用基因型分析来了解个体中该药物代谢酶的活性,期望既能提高药物治疗水平同时又降低不良反应的发生。有关CYP2C19的研究在此方面已树立了一个成功的典范。     

细胞色素P450基因多态性与药物代谢研究进展

细胞色素P450（cytochrome P450,CYP450）在人体药物代谢过程中起着非常重要的作用并参与代谢80%以上的临床药物。由于CYP450在不同种族和不同人群中存在基因多态性,从而造成药物反应的个体差异,一度成为药物基因组学研究的热点。通过查阅国外相关文献,综述了近年来关于CYP1A2、CYP2C9、CYP2C19、CYP2D6和CYP3A4五种主要的药物代谢酶的基因多态性和药物代谢的研究进展,为临床指导个体化用药、避免药物不良反应和新药研发提供科学参考依据。     

催化吲哚生成靛蓝的细胞色素P450BM-3 定向进化研究

以催化吲哚产生的靛蓝在 630 nm 处具有特殊的吸收峰为高通量筛选指标,将来源于 Bacillus megaterium 的细胞色素 P450BM-3 单加氧酶的基因序列用易错聚合酶链式反应进行定向进化,通过多轮突变,在原有的能产靛蓝的高活力突变酶的基础上成功获得了三个高于亲本酶的突变酶,突变酶的酶活分别是亲本酶的 6.6 倍 (hml001) , 9.6 倍 (hml002) 和 5.3 倍 (hml003) ,并对突变酶的动力学参数进行了分析 . 突变酶 DNA 测序的结果表明, hml001 含有一个有义氨基酸置换 I39V , hml002 含有三个有义氨基酸置换 D168N , A225V , K440N , hml003 含有一个有义氨基酸置换 E435D ,这些突变位点有些远离底物结合部位,有些位于底物结合部位 .     

Quantitative Assessment of the Effect of Cytochrome P450 2C9 Gene Polymorphism and Colorectal Cancer

CYP2C9 enzyme activity is involved in the metabolism of substances related to colorectal cancer (CRC), and it is functionally linked to a genetic polymorphism. Two allelic variants of the CYP2C9 gene, namely CYP2C9*2 and CYP2C9*3, differ from wild-type CYP2C9*1 by single amino acid substitutions. These mutated alleles encode enzymes with altered properties that are associated with impaired metabolism. In the past decade, a number of case-control studies have been carried out to investigate the relationship between the CYP2C9 polymorphism and CRC susceptibility, but the results were conflicting. To investigate this inconsistency, we performed a meta-analysis of 13 studies involving a total of 20,879 subjects for CYP2C9*2 and *3 polymorphisms to evaluate the effect of CYP2C9 on genetic susceptibility for CRC. Overall, the summary odds ratio of CRC was 0.94 (95%CI: 0.87–1.03, P = 0.18) and 1.00 (95%CI: 0.86–1.16, P = 0.99) for CYP2C9 *2 and *3 carriers, respectively. No significant results were observed in heterozygous and homozygous when compared with wild genotype for these polymorphisms. In the stratified analyses according to ethnicity, sample size, diagnostic criterion, HWE status and sex, no evidence of any gene-disease association was obtained. Our result suggest that the *2, *3 polymorphisms of CYP2C9 gene are not associated with CRC susceptibility.     

Structural Characterization of Human Cytochrome P450 2C19: ACTIVE SITE DIFFERENCES BETWEEN P450s 2C8, 2C9, AND 2C19*?

To identify the structural features underlying the distinct substrate and inhibitor profiles of P450 2C19 relative to the closely related human enzymes, P450s 2C8 and 2C9, the atomic structure (Protein Data Bank code 4GQS) of cytochrome P450 2C19 complexed with the inhibitor (2-methyl-1-benzofuran-3-yl)-(4-hydroxy-3,5-dimethylphenyl)methanone (Protein Data Bank chemical component 0XV) was determined to 2.87 Å resolution by x-ray crystallography. The conformation of the peptide backbone of P450 2C19 is most similar to that of P450 2C8, but the substrate-binding cavity of P450 2C8 is much larger than that of P450 2C19 due to differences in the amino acid residues that form the substrate-binding cavities of the two enzymes. In contrast, the substrate-binding cavity of P450 2C19 is much more similar in size to that of the structure of the P450 2C9 flurbiprofen complex than to that of a modified P450 2C9 or that of P450 2C8. The cavities of the P450 2C19 0XV complex and the P450 2C9 flurbiprofen complex differ, however, because the helix B-C loops of the two enzymes are dissimilar. These conformational differences reflect the effects of adjacent structural elements that interact with the B-C loops and that differ between the two enzymes. The availability of a structure for 2C19 will facilitate computational approaches for predictions of substrate and inhibitor binding to this enzyme.     

细胞色素P450与癌症基因治疗

细胞色素Ｐ45 0基因与癌症化疗潜药(该类潜药可通过Ｐ45 0催化的加单氧酶反应而活化 )结合的癌症基因疗法引人注意[1]一些抗癌药物可被Ｐ45 0酶系代谢 (表1 )。环磷酰胺 (ＣＰＡ )、异环磷酰胺 (ｉｆｏｓ ｆａｍｉｄｅ)、甲基苄肼、甲苄肼 ( ｐｒｏｃａｒｂａｚｉｎｅ)和氮烯咪胺 (ｄａｃａｒｂａｚｉｎｅ) ,经特定Ｐ45 0酶系的代谢所产生的中间物具有抗癌活性。硫代ＴＥＰＡ、阿霉素、依托泊甙 (ｅｔｏｐｏｓｉｄｅ)和三苯氧胺 (ｔａｍｏｘｉｆｅｎ)本身具有抗癌活性 ,但通过Ｐ45 0代谢形成的具有细胞毒性的代谢物 ,抗癌活性可得到加强。还…     

Advances in Molecular Modeling of Human Cytochrome P450 Polymorphism

Cytochrome P450 (CYP) is a supergene family of metabolizing enzymes involved in the phase I metabolism of drugs and endogenous compounds. CYP oxidation often leads to inactive drug metabolites or to highly toxic or carcinogenic metabolites involved in adverse drug reactions (ADR). During the last decade, the impact of CYP polymorphism in various drug responses and ADR has been demonstrated. Of the drugs involved in ADR, 56% are metabolized by polymorphic phase I metabolizing enzymes, 86% among them being CYP. Here, we review the major CYP polymorphic forms, their impact for drug response and current advances in molecular modeling of CYP polymorphism. We focus on recent studies exploring CYP polymorphism performed by the use of sequence-based and/or protein-structure-based computational approaches. The importance of understanding the molecular mechanisms related to CYP polymorphism and drug response at the atomic level is outlined.     

Quantitative Assessment of the Influence of Cytochrome P450 1A2 Gene Polymorphism and Colorectal Cancer Risk

Cytochrome P450 1A2 (CYP1A2) encodes a member of the cytochrome P450 superfamily of enzymes, which play a central role in activating and detoxifying many carcinogens and endogenous compounds thought to be involved in the development of colorectal cancer (CRC). The CYP1A2*C (rs2069514) and CYP1A2*F (rs762551) polymorphism are two of the most commonly studied polymorphisms of the gene for their association with risk of CRC, but the results are conflicting. To derive a more precise estimation of the relationship between CYP1A2 and genetic risk of CRC, we performed a comprehensive meta-analysis which included 7088 cases and 7568 controls from 12 published case-control studies. In a combined analysis, the summary per-allele odds ratio for CRC was 0.91 (95% CI: 0.83–1.00, P = 0.04), and 0.91 (95% CI: 0.68–1.22, P = 0.53), for CYP1A2 *F and *C allele, respectively. In the subgroup analysis by ethnicity, significant associations were found in Asians for CYP1A2*F and CYP1A2*C, while no significant associations were detected among Caucasian populations. Similar results were also observed using dominant genetic model. Potential sources of heterogeneity were explored by subgroup analysis and meta-regression. No significant heterogeneity was detected in most of comparisons. This meta-analysis suggests that the CYP1A2 *F and *C polymorphism is a protective factor against CRC among Asians.     

Meta-Analysis of Cytochrome P-450 2C9 Polymorphism and Colorectal Cancer Risk

Background

CYP2C9 encodes a member of the cytochrome P450 superfamily of enzymes which play a central role in activating and detoxifying many carcinogens and endogenous compounds thought to be involved in the development of colorectal cancer (CRC). In the past decade, the relationship between CYP2C9 common polymorphisms (R144C and I359L) and CRC has been reported in various ethnic groups; however, these studies have yielded contradictory results. To investigate this inconsistency, we performed this meta-analysis.

Methods

Databases including Pubmed, EMBASE, Web of Science and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association.

Results

A total of 13 articles involving 9,463 cases and 11,416 controls were included. Overall, the summary odds ratio of CRC was 0.98 (95% CI: 0.89−1.06) and 0.99 (95% CI: 0.87−1.14) for CYP2C9 144C and 359L alleles, respectively. No significant results were observed using dominant or recessive genetic model for these polymorphisms. In the stratified analyses according to ethnicity and sex, no evidence of any gene-disease association was obtained.

Conclusions

This meta-analysis suggests that the CYP2C9 may not be associated with colorectal cancer development.     

Cytochrome P450

Since 1993, three new cytochrome P450 X-ray structures have been determined, giving a total of four known structures. Two of the new structures are in the substrate-free form and one is substrate-bound. These new structures, together with a wealth of mutagenesis studies on various P450s, have provided considerable information on what structural features control substrate specificity in P450s. In addition, some important insights into the catalytic mechanism have been made.