Wang K Y, Gerena L, Swaminathan S, Bolton P H
Chemistry Department, Wesleyan University, Middletown, CT 06459, USA.
Nucleic Acids Res. 1995 Mar 11;23(5):844-8. doi: 10.1093/nar/23.5.844.
The paramagnetic metal ion Mn2+ has been used to probe the electrostatic potentials of a DNA quadruplex that has two quartets with an overall fold of the chair type. A quadruplex with a basket type structure has also been examined. The binding of the paramagnetic ion manganese to these quadruplex DNAs has been investigated by solution state electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopies. The EPR results indicate that the DNA aptamer, d(GGTTGGTGTGGTTGG), binds two manganese ions and that the binding constants for each of these sites is approximately 10(5) M-1. The NMR results indicate that the binding sites of the manganese are in the narrow grooves of this quadruplex DNA. The binding sites of the DNA quadruplex formed by dimers of d(GGGGTTTTGGGG) which forms a basket structure are also in the narrow groove. These results indicate that the close approach of phosphates in the narrow minor grooves of the quadruplex structures provide strong binding sites for the manganese ions and that EPR and NMR monitoring of manganese binding can be used to distinguish between the different types of quadruplex structures.
顺磁性金属离子Mn2+已被用于探测一种具有两个四重态且整体折叠为椅型的DNA四链体的静电势。还研究了一种具有篮型结构的四链体。通过溶液态电子顺磁共振（EPR）和核磁共振（NMR）光谱学研究了顺磁性离子锰与这些四链体DNA的结合。EPR结果表明，DNA适配体d(GGTTGGTGTGGTTGG)结合两个锰离子，且每个位点的结合常数约为10(5) M-1。NMR结果表明，锰的结合位点位于该四链体DNA的窄沟中。由形成篮型结构的d(GGGGTTTTGGGG)二聚体形成的DNA四链体的结合位点也在窄沟中。这些结果表明，四链体结构窄小沟中的磷酸盐紧密靠近为锰离子提供了强结合位点，并且通过EPR和NMR监测锰的结合可用于区分不同类型的四链体结构。
