Ababneh Anas M, Large C C, Georghiou S
Molecular Biophysics Laboratory, Department of Physics, The University of Tennessee, Knoxville, Tennessee 37996, USA.
Biophys J. 2003 Aug;85(2):1111-27. doi: 10.1016/S0006-3495(03)74548-2.
Toward the goal of understanding how open basepairs in DNA interact with their heterogeneous environment, we have studied the steady-state intrinsic fluorescence properties of the purine and pyrimidine deoxynucleosides in organic solvents in the presence of small amounts of water. The organic solvents used in the present study were: n-butanol, acetonitrile, methanol, n-propanol, isopropanol, and isobutanol. For n-butanol and acetonitrile, which have a high degree of amphiphilicity and weak hydrogen bonding ability, respectively, the fluorescence spectral properties of the purines are found to depend on the sequence of steps in which the aqueous mixtures were formed. By contrast, no such dependence was observed in the mixtures with any of the other solvents used in the present study. Moreover, no such dependence was observed for the pyrimidines. These findings suggest that the final solvation network around the purines is dependent on the nature of the environment to which they were initially exposed. This would tend to present an impediment to the closing of AT or GC basepairs in DNA that become open as a result of structural fluctuations, DNA bending, or protein-DNA interactions.
为了理解DNA中的开放碱基对如何与其异质环境相互作用，我们研究了在少量水存在下，嘌呤和嘧啶脱氧核苷在有机溶剂中的稳态固有荧光特性。本研究中使用的有机溶剂有：正丁醇、乙腈、甲醇、正丙醇、异丙醇和异丁醇。对于分别具有高度两亲性和弱氢键能力的正丁醇和乙腈，发现嘌呤的荧光光谱特性取决于形成水性混合物的步骤顺序。相比之下，在本研究中使用的任何其他溶剂的混合物中均未观察到这种依赖性。此外，嘧啶也未观察到这种依赖性。这些发现表明，嘌呤周围的最终溶剂化网络取决于它们最初所暴露环境的性质。这可能会对由于结构波动、DNA弯曲或蛋白质-DNA相互作用而打开的DNA中的AT或GC碱基对的闭合形成阻碍。
