Bimolecular quadruplexes and their transitions to higher-order molecular structures detected by ESI-FTICR-MS
Bimolecular quadruplexes and their transitions to higher-order molecular structures detected by ESI-FTICR-MS
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ESI-FTICR-MS 检测双分子四链体及其向高阶分子结构的转变
DOI：
10.1016/j.jasms.2007.05.003
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发表时间：
2007-08-01
影响因子：
3.2
通讯作者：
Yu, Zhan
中科院分区：
文献类型：
--
作者：
Guo, Xinhua;Liu, Shuying;Yu, Zhan
用电喷雾离子化傅里叶变换离子回旋共振质谱（ESI-FTICR-MS）在气相中检测到四个四链体，它们是在乙酸铵溶液中由紧密相关的DNA链的端粒序列自组装而成的：d（G（4）T（4）G（4）），d（G（3）T（4）G（4）），d（G（3）T（4）G（3））和d（G（4）T（4）G（3））。双分子四链体在气相中与相同数量的NH 4+缔合，正如NMR显示它们在溶液中所缔合的那样。在溶液中形成的四链体结构保持在气相中。此外，质谱表明，由链d（G（3）T（4）G（3））和d（G（4）T（4）G（3））产生的双分子四链体是不稳定的，随着溶液中NH 4+浓度的增加，它们被转化为三分子和四分子结构。圆二色性（CD）光谱揭示了链化学计量转换过程中的结构变化，其中四链体中链的相对取向从反平行变为平行排列。在链d（G（4）T（4）G（3））中观察到这种变化，但在链d（G（3）T（4）G（3））中没有观察到这种变化。目前的工作提供了一个重要的洞察各种DNA四链体的形成，特别是高阶物种。
Four individual quadruplexes, which are self-assembled in ammonium acetate solution from telomeric sequences of closely related DNA strands - d(G(4)T(4)G(4)), d(G(3)T(4)G(4)), d(G(3)T(4)G(3)), and d(G(4)T(4)G(3)) - have been detected in the gas phase using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The bimolecular quadruplexes associate with the same number of NH4+ in the gas phase as NMR shows that they do in solution. The quadruplex structures formed in solution are maintained in the gas phase. Furthermore, the mass spectra show that the bimolecular quadruplexes generated by the strands d(G(3)T(4)G(3)) and d(G(4)T(4)G(3)) are unstable, being converted into trimolecular and tetramolecular structures with increasing concentrations of NH4+ in the solution. Circular dichroism (CD) spectra reveal structural changes during the process of strand stoichiometric transitions, in which the relative orientation of strands in the quadruplexes changes from an antiparallel to a parallel arrangement. Such changes were observed for the strand d(G(4)T(4)G(3)), but not for the strand d(G(3)T(4)G(3)). The present work provides a significant insight into the formation of various DNA quadruplexes, especially the higher-order species.