Hydration reactions of sodiated and potassiated nucleic acid bases (uracil, thymine, cytosine, and adenine) produced by electrospray have been studied in a gas phase using the pulsed ion-beam high-pressure mass spectrometer. The thermochemical properties, ΔHon, ΔSon, and ΔGon, for the hydrated systems were obtained from hydration equilibrium measurement. The structural aspects of the hydrated complexes are discussed in conjunction with available literature data. The correlation between water binding energies in the hydrated complexes and the corresponding metal ion affinities of nucleobases suggests that a significant (if not dominant) amount of the canonical structure of cytosine undergoes tautomerization during electrospray ionization, and the thermochemical values for cationized cytosine probably correspond to a mixture of tautomeric complexes.
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机译:使用脉冲离子束高压质谱仪在气相中研究了电喷雾产生的钠化和钾化核酸碱基(尿嘧啶,胸腺嘧啶,胞嘧啶和腺嘌呤)的水合反应。通过水合平衡测量获得了水合体系的热化学性质,ΔH o sup> n,ΔS o sup> n和ΔG o sup> n。结合可用的文献数据讨论了水合配合物的结构方面。水合复合物中水结合能与相应的核碱基金属离子亲和力之间的相关性表明,在电喷雾电离过程中,大量(如果不是主要的)胞嘧啶正典结构发生互变异构,阳离子化胞嘧啶的热化学值可能对应于互变异构复合物的混合物。
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