Effects of hydration, ion release, and excluded volume on the melting of triplex and duplex DNA
Effects of hydration, ion release, and excluded volume on the melting of triplex and duplex DNA
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DOI：
10.1021/bi9820154
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发表时间：
1999-01-05
期刊：
影响因子：
2.9
通讯作者：
Chaires, JB
中科院分区：
文献类型：
--
作者：
Spink, CH;Chaires, JB
DNA双链和三链结构的稳定性不仅取决于碱基配对或三倍或静电相互作用等分子力，而且对其水环境也很敏感。本文介绍了大肠杆菌和聚（dA）熔融的数据。聚（dT）双链DNA和聚（dT）双链DNA。聚（dT）三倍体在多种介质中的渗透状态和介质含盐量的贡献进行了评价。研究了体积排斥对DNA结构稳定性的影响。通过在低分子量渗透胁迫条件下的热转变测量，发现双链熔融时每碱基对释放4个水分子，三链转化为单链和双链时释放1个水分子。还确定了在乙二醇溶液中Na+反离子结合的影响，从而评估了反离子结合随水活度的变化。数据表明，随着水活度的降低，双分子和三分子的反离子结合程度有一定程度的降低。最后，使用较大的聚乙二醇辅助溶质，评估溶质对体积排除熔化的影响，并将结果与排除体积的简单几何模型相关联。这些结果表明，在双链或三链环境中，DNA的稳定性对一些重要条件很敏感，因此，这些条件会影响DNA的构象和反应性。
The stability of DNA duplex and tripler structures not only depends on molecular forces such as base pairing or tripling or electrostatic interactions but also is sensitive to its aqueous environment. This gaper presents data on the melting of Escherichia coli and poly(dA).poly(dT) duplex DNA and on the poly(dT).poly(dA).poly(dT) tripler in a variety of media to assess the contributions from the osmotic status and salt content of the media. The effects of volume exclusion on the stability of the DNA structures are also studied. From thermal transition measurements in the presence of low-molecular weight osmotic stressors, the number of water molecules released upon melting is found to be four waters per base pair for duplex melting and one water for the conversion of tripler to single-strand and duplex. The effects of Na+ counterion binding are also determined in ethylene glycol solutions so that the variation of counterion binding with water activity is evaluated. The data show that there is a modest decrease in the extent of counterion binding for both duplex and tripler as water activity decreases. Finally, using larger polyethylene glycol cosolutes, the effects on melting of volume exclusion by the solutes are assessed, and the results correlated with simple geometric models for the excluded volume. These results point out that DNA stability is sensitive to important conditions in the environment of the duplex or tripler, and thus, conformation and reactivity can be influenced by these solution conditions.