Direct Evidence for Tautomerization of the Uracil Moiety within the Pb2+/Uridine-5鈥?monophosphate Complex: A Combined Tandem Mass Spectrometry and IRMPD study

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• 作者：Jean-Yves Salpin ; Se虂bastien Guillaumont ; Daniel Ortiz ; Jeanine Tortajada ; Philippe Mai虃tre
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：August 15, 2011
• 年：2011
• 卷：50
• 期：16
• 页码：7769-7778
• 全文大小：1014K
• 年卷期：v.50,no.16(August 15, 2011)
• ISSN：1520-510X

文摘

The structure of the [Pb(UMP)-H]⁺ (UMP = uridine-5鈥?monophosphate) complex was studied in the gas phase by combining electrospray ionization (ESI), tandem mass spectrometry, and mid-infrared multiple photon dissociation (IRMPD) spectroscopy. The results obtained show that Pb²⁺ ions interact not only with the deprotonated phosphate group but also with a carbonyl group of the nucleobase moiety by folding of the mononucleotide, resulting in macrochelates that are not likely to be present in solution. Comparison between the IRMPD and DFT-computed spectra suggests that the ESI-generated complex likely corresponds to a mixture of several structures, and establishes the enolic tautomers as the most abundant species for the [Pb(UMP)-H]⁺ ion, while the very weak IRMPD signal observed at 1763 cm^鈥? points to a minor population of oxo forms. Our data also suggest that losing the nucleobase residue under CID conditions does not necessarily mean a lack of interaction between the metal and the nucleobase moiety, as commonly reported in the literature for large oligonucleotides.