Mechanism of rat liver DNA methyltransferase interaction with anti-benzo[a]pyrenediol epoxide modified DNA templates.
Mechanism of rat liver DNA methyltransferase interaction with anti-benzo[a]pyrenediol epoxide modified DNA templates.
复制标题
大鼠肝脏 DNA 甲基转移酶与抗苯并[a]芘二醇环氧化物修饰的 DNA 模板相互作用的机制。
DOI：
10.1021/bi00318a008
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发表时间：
1984
期刊：
影响因子：
2.9
通讯作者：
Lapeyre,JN
中科院分区：
文献类型：
--
作者：
Ruchirawat,M;Becker,FF;Lapeyre,JN
放大图片作者：Frederick F. Becker和Jean-Numa Lapeyre* 摘要：我们研究了1500倍纯化的大鼠肝DNA甲基转移酶（DMase）在天然藤黄微球菌DNA（ML-DNA）和含有共价结合的（+）-7/3，8a-二羟基-9a，10a-环氧-7，8，9，10-四氢苯并[a]-芘的聚（dC-dG）模板上催化的甲基化反应（azzfz '-BPDE），苯并[a]芘的主要代谢产物，具有强致癌性。由于真核生物DNA甲基转移酶识别DNA中的二核苷酸5 ′ d [CG]作为甲基化的底物，因此，我们用模型多核苷酸poly（dC-dG）来详细研究它们的相互作用方式和对掺入的影响。使用这些BPDE修饰的模板中的任何一种，甲基化的逐渐抑制与BPDE取代量的增加相关。BPDE-dG加合物的效果没有改变相对于未改性或BPDE改性的聚（dC-dG）（km= 10/ttM）中d [CG]浓度的表观km，但降低了相对表观Kmax。在测定预先形成的酶-DNA复合物的盐扰动的试验中，未观察到对未取代或致癌物修饰的模板的相对稳定性的变化，因此，排除了这种相互作用的离子组分的任何变化。然而，在竞争型实验中，
Mathuros Ruchirawat, Frederick F. Becker, and Jean-Numa Lapeyre* abstract: We investigated the methylation reaction catalyzed by 1500-fold purified rat liver DNA methyltransferase (DMase) on native Micrococcal luteus DNA (ML-DNA) and poly (dC-dG) templates containing covalently bound (+)-7/3, 8a-dihydroxy-9a, 1 Oa-epoxy-7, 8, 9, 10-tetrahydrobenzo [a]-pyrene (azzfz'-BPDE), the strongly carcinogenic, principal metabolite of benzo [a] pyrene. Since eukaryotic DNA me-thyltransferases recognize the dinucleotide 5'd [CG] in DNA as a substrate for methylation, the model polynucleotide poly (dC-dG) was used tostudy in more detail themode of interaction and effect on incorporation. With either of these BPDE-modified templates, a progressive inhibition of me-thylation was correlated with increasing amount of BPDE substitution. The effect of BPDE-dG adducts did not alter the apparent km with respect to the concentration of d [CG] in either unmodified or BPDE-modified poly (dC-dG)(km= 10/ttM) but lowered the relative apparent Kmax. In assays in which perturbation by salt of preformed enzyme-DNA com-plex is measured, no change in the relative stability to either unsubstituted or the carcinogen-modified template was noted, thus, excluding any change in the ionic component of this interaction. However, in competition-type experiments,