Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA.
Department of Chemistry, University of Utah, Salt Lake City, UT, 84112, USA.
J Am Soc Mass Spectrom. 2019 Nov;30(11):2318-2334. doi: 10.1007/s13361-019-02300-9. Epub 2019 Aug 21.
The 2'-substituents distinguish DNA from RNA nucleosides. 2'-O-methylation occurs naturally in RNA and plays important roles in biological processes. Such 2'-modifications may alter the hydrogen-bonding interactions of the nucleoside and thus may affect the conformations of the nucleoside in an RNA chain. Structures of the protonated 2'-O-methylated pyrimidine nucleosides were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy, assisted by electronic structure calculations. The glycosidic bond stabilities of the protonated 2'-O-methylated pyrimidine nucleosides, [Nuom+H], were also examined and compared to their DNA and RNA nucleoside analogues via energy-resolved collision-induced dissociation (ER-CID). The preferred sites of protonation of the 2'-O-methylated pyrimidine nucleosides parallel their canonical DNA and RNA nucleoside analogues, [dNuo+H] and [Nuo+H], yet their nucleobase orientation and sugar puckering differ. The glycosidic bond stabilities of the protonated pyrimidine nucleosides follow the order: [dNuo+H] < [Nuo+H] < [Nuom+H]. The slightly altered structures help explain the stabilization induced by 2'-O-methylation of the pyrimidine nucleosides.
2'-取代基区分 DNA 和 RNA 核苷。2'-O-甲基化在 RNA 中自然发生，在生物过程中发挥重要作用。这种 2'-修饰可能改变核苷的氢键相互作用，从而可能影响 RNA 链中核苷的构象。通过红外多光子解离 (IRMPD) 作用光谱法，并辅以电子结构计算，研究了质子化 2'-O-甲基嘧啶核苷的结构。还通过能量分辨碰撞诱导解离 (ER-CID) 研究并比较了质子化 2'-O-甲基嘧啶核苷、[Nuom+H]与其 DNA 和 RNA 核苷类似物的糖苷键稳定性。2'-O-甲基嘧啶核苷的质子化优先位点与其规范的 DNA 和 RNA 核苷类似物 [dNuo+H] 和 [Nuo+H] 平行，但它们的碱基取向和糖构象不同。质子化嘧啶核苷的糖苷键稳定性遵循以下顺序：[dNuo+H] < [Nuo+H] < [Nuom+H]。略微改变的结构有助于解释 2'-O-甲基化对嘧啶核苷的稳定作用。
