Effects of coordination of diammineplatinum(II) with DNA on the activities of Escherichia coli DNA polymerase I.
Effects of coordination of diammineplatinum(II) with DNA on the activities of Escherichia coli DNA polymerase I.
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二氨铂(II)与DNA配位对大肠杆菌DNA聚合酶I活性的影响。
DOI：
10.1021/bi00417a031
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
E. Holler
中科院分区：
文献类型：
--
作者：
F. Bernges;E. Holler
顺式和反式二氯二氨铂 (II) 与 DNA 的反应对大肠杆菌 DNA 聚合酶 I 的 DNA 合成、3'-5' 核酸外切酶（校对）和 5'-3' 核酸外切酶（修复）活性的影响进行了测量。两种异构体通过增加铂化 DNA 的 Km 值和降低 Vmax 值来抑制聚合酶的 DNA 合成活性，但对于铂化 DNA 则不然。核苷 5'-三磷酸作为不同的底物。这种抑制是铂化 DNA 和 DNA 聚合酶之间结合亲和力降低以及铂化诱导的模板链和引物链分离的结果。链分离提高了从铂化 DNA 中 3'-5' 切除 [3H]dCMP 的初始速率（校对），同时降低了核苷酸的总切除水平。与校对活性相反，5'-3'核酸外切酶活性（修复）区分与顺式和反式二氯二氨铂(II)反应的DNA。虽然顺式异构体的初始速率和总切除都受到抑制，但反式异构体几乎不受影响。这种差异效应可以解释为什么抑制细菌生长需要比顺式二氯二氨铂 (II) 浓度高得多的浓度。
The effects of the reaction of cis- and trans-diamminedichloroplatinum(II) with DNA have been measured with regard to DNA synthesis, 3'-5' exonuclease (proofreading), and 5'-3' exonuclease (repair) activities of Escherichia coli DNA polymerase I. Both isomers inhibit DNA synthetic activity of the polymerase through an increase in Km values and a decrease in Vmax values for platinated DNA but not for the nucleoside 5'-triphosphates as the varied substrates. The inhibition is a consequence of lowered binding affinity between platinated DNA and DNA polymerase, and of a platination-induced separation of template and primer strands. Strand separation enhances initial rates of 3'-5' excision of [3H]dCMP from platinated DNA (proofreading), while total excision levels of nucleotides are decreased. In contrast to proofreading activity, the 5'-3' exonuclease activity (repair) discriminates between DNA which had reacted with cis- and with trans-diamminedichloroplatinum(II). While both initial rates and total excision are inhibited for the cis isomer, they are almost not affected for the trans isomer. This differential effect could explain why bacterial growth inhibition requires much higher concentrations of trans- than cis-diamminedichloroplatinum(II).