Water-DNA interactions as studied by X-ray and neutron fibre diffraction
Water-DNA interactions as studied by X-ray and neutron fibre diffraction
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DOI：
10.1098/rstb.2004.1501
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发表时间：
2004-08-29
影响因子：
6.3
通讯作者：
Mahendrasingam, A
中科院分区：
文献类型：
--
作者：
Fuller, W;Forsyth, T;Mahendrasingam, A
X射线纤维衍射研究表明，水和DNA双螺旋之间的相互作用具有高度的立体化学特异性。这方面的证据来自数据，这些数据表明，DNA在纤维中所呈现的分子构象具有高度的可重复性，并且这些构象之间的水合驱动的转变是完全可逆的。这些构象转变是通过改变纤维环境的相对湿度以及其含水量来诱导的。立体化学特异性的进一步证据来自观察到的假定构象对纤维离子含量和DNA核苷酸序列的依赖性。对于某些转换，立体化学途径的信息来自实时X-射线纤维衍射使用同步辐射;水的位置相对于双螺旋的一些DNA构象的信息来自中子纤维衍射。DNA的纤维衍射研究的结构信息得到了寡核苷酸的X射线单晶研究信息的补充。如果涉及DNA的生化过程已经发展到利用DNA纤维和寡核苷酸单晶中观察到的结构特征，那么开发水环境替代品的挑战预计将非常严峻。
X-ray fibre-diffraction studies indicate a high degree of stereochemical specificity in interactions between water and the DNA double helix. Evidence for this comes from data that show that the molecular conformations assumed by DNA in fibres are highly reproducible and that the hydration-driven transitions between these conformations are fully reversible. These conformational transitions are induced by varying the relative humidity of the fibre environment and hence its water content. Further evidence for stereochemical specificity comes from the observed dependence of the conformation assumed on the ionic content of the fibre and the nucleotide sequence of the DNA. For some transitions, information on stereochemical pathways has come from real-time X-ray fibre diffraction using synchrotron radiation; information on the location of water with respect to the double helix for a number of DNA conformations has come from neutron fibre diffraction. This structural information from fibre-diffraction studies of DNA is complemented by information from X-ray single-crystal studies of oligonucleotides. If the biochemical processes involving DNA have evolved to exploit the structural features observed in DNA fibres and oligonucleotide single crystals, the challenges in developing alternatives to a water environment can be expected to be very severe.