Spectroscopic and calorimetric characterizations of DNA duplexes containing 2-aminopurine
Spectroscopic and calorimetric characterizations of DNA duplexes containing 2-aminopurine
复制标题
DOI：
10.1021/bi9614545
复制
发表时间：
1996-09-24
期刊：
影响因子：
2.9
通讯作者：
Breslauer, KJ
中科院分区：
文献类型：
--
作者：
Law, SM;Eritja, R;Breslauer, KJ
碱基类似物2 - 氨基嘌呤（AP）在细菌和噬菌体中强烈促进A·T到G·C以及G·C到A·T的转换。在DNA复制过程中，主要的诱变事件是形成含有AP·C位点的异源双链，其频率远高于形成相应含有A·C位点的异源双链。目前尚不清楚AP诱导的诱变是否与AP·C位点和A·C位点的热力学性质差异相关，也不清楚涉及DNA聚合酶的相互作用是否起控制作用。为了解决这个具体问题，并且更普遍地描述含AP的双链体的特性，我们结合光谱学和量热技术来确定六种11聚体双链体的热力学性质。这些双链体的序列除了可变的中心碱基对不同外完全相同，中心碱基对可以是A·T、A·C、AP·T、AP·C、AP·A或AP·G，我们用此来命名每个双链体。对这六种双链体通过光学和量热方法获得的热学和热力学数据的分析和解释表明，中心碱基对的相对稳定作用为A·T > AP·T > AP·C > AP·A > AP·G > A·C，含AP·C的双链体比含A·C的双链体稳定得多。总体而言，我们的结果表明，在掺入过程中，DNA聚合酶对碱基对的区分部分地受到新形成碱基对热力学稳定性差异的影响。
The base analog 2-aminopurine (AP) strongly promotes A . T to G . C and G . C to A . T transitions in bacteria and bacteriophage. During DNA replication the primary mutagenic event involves formation of a heteroduplex with an AP . C site at a much higher frequency than formation of the corresponding heteroduplex with an A . C site. It is not known if AP-induced mutagenesis correlates with differences in the thermodynamic properties of an AP . C versus an A . C site, or whether interactions involving DNA polymerases are controlling, To address this specific question, and more generally to characterize AP-containing duplexes, we have used a combination of spectroscopic and calorimetric techniques to determine the thermodynamic properties of six Il-mer duplexes. The sequences of these duplexes are identical except for the identity of the variable central base pair which can be either A . T, A . C, AP . T, AP . C, AP . A, or AP . G, and which we use to designate each duplex. Analyses and interpretation of the optically and calorimetrically derived thermal and thermodynamic data on these six duplexes reveal the relative stabilizing influence of the central base pairs to be A . T > AP . T > AP . C > AP . A > AP . G > A . C, with the AP . C-containing duplex being significantly more stable than the A . C-containing duplex, In the aggregate, our results suggest that during incorporation, base pair discrimination by DNA polymerases is influenced, in part, by differences in the thermodynamic stabilities of the newly formed base pairs.