Clustering of nucleosides in the presence of alkali metals: Biologically relevant quartets of guanosine, deoxyguanosine and uridine observed by ESI-MS/MS
Clustering of nucleosides in the presence of alkali metals: Biologically relevant quartets of guanosine, deoxyguanosine and uridine observed by ESI-MS/MS
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DOI：
10.1002/jms.405
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发表时间：
2003-01-01
影响因子：
2.3
通讯作者：
Cooks, RG
中科院分区：
文献类型：
--
作者：
Aggerholm, T;Nanita, SC;Cooks, RG
在碱金属存在下记录的核苷电喷雾电离 (ESI) 质谱显示了碱金属离子结合的四重态和其他簇，这可能对理解 DNA 和 RNA 中的非共价相互作用具有影响。鸟苷和脱氧鸟苷的四聚体以及它们的元簇（簇的簇），被碱金属阳离子化，被观察为异常丰富的幻数簇。在气相中对这些物质的观察与之前的凝聚相研究相似，这些研究表明鸟嘌呤衍生物可以在金属阳离子存在的情况下在溶液中形成四联体和四联体的元簇。这种平行行为以及内部证据表明鸟苷四聚体中的键合涉及碱基而不是糖单元。已知核碱基胸腺嘧啶和尿嘧啶在气相中与 K+、Cs+ 和 NH4+ 形成幻数五聚体加合物。与此形成鲜明对比的是，我们现在表明核苷尿苷和脱氧胸苷不形成相应碱基特有的五聚体簇。糖的更微妙的影响在以下事实中是明显的：腺苷和胞苷与碱金属形成许多高阶簇，而脱氧腺苷和脱氧胞苷没有表现出簇。这表明dG和rG四聚体中碱基之间的氢键是簇中的主要相互作用，因此将核糖基团改变为脱氧核糖（反之亦然）通常影响不大。然而，RNA核苷的额外羟基增强了腺苷和胞苷高阶聚集体的非选择性形成，导致缺乏高度稳定的幻数簇。一些簇是电离 (ESI) 过程中聚集的结果，而其他簇似乎是所检查溶液固有的。版权所有 (C) 2003 John Wiley Sons, Ltd.
Electrospray ionization (ESI) mass spectra of nucleosides, recorded in the presence of alkali metals, display alkali metal ion-bound quartets and other clusters that may have implications for understanding noncovalent interactions in DNA and RNA. The tetramers of guanosine and deoxyguanosine and also their metaclusters (clusters of clusters), cationized by alkali metals, were observed as unusually abundant magic number clusters. The observation of these species in the gas phase parallels previous condensed-phase studies, which show that guanine derivatives can form quartets and metaclusters of quartets in solution in the presence of metal cations. This parallel behavior and also internal evidence suggest that bonding in the guanosine tetramers involves the bases rather than the sugar units. The nucleobases thymine and uracil are known to form magic number pentameric adducts with K+, Cs+ and NH4+ in the gas phase. In sharp contrast, we now show that the nucleosides uridine and deoxythymidine do not form the pentameric clusters characteristic of the corresponding bases. More subtle effects of the sugars are evident in the fact that adenosine and cytidine form numerous higher order clusters with alkali metals, whereas deoxyadenosine and deoxycytidine show no clustering. It is suggested that hydrogen bonding between the bases in the tetramers of dG and rG are the dominant interactions in the clusters, hence changing the ribose group to deoxyribose (and vice versa) generally has little effect. However, the additional hydroxyl group of RNA nucleosides enhances the non-selective formation of higher-order aggregates for adenosine and cytidine and results in the lack of highly stable magic number clusters. Some clusters are the result of aggregation in the course of ionization (ESI) whereas others appear to be intrinsic to the solution being examined. Copyright (C) 2003 John Wiley Sons, Ltd.