Cruz-Ortiz Andrés F, Rossa Maximiliano, Berthias Francis, Berdakin Matías, Maitre Philippe, Pino Gustavo A
Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC), CONICET - UNC, Ciudad Universitaria , X5000HUA Córdoba, Argentina.
Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria , X5000HUA Córdoba, Argentina.
J Phys Chem Lett. 2017 Nov 16;8(22):5501-5506. doi: 10.1021/acs.jpclett.7b02140. Epub 2017 Oct 31.
Gas phase protonated guanine-cytosine (CGH) pair was generated using an electrospray ionization source from solutions at two different pH (5.8 and 3.2). Consistent evidence from MS/MS fragmentation patterns and differential ion mobility spectra (DIMS) point toward the presence of two isomers of the CGH pair, whose relative populations depend strongly on the pH of the solution. Gas phase infrared multiphoton dissociation (IRMPD) spectroscopy in the 900-1900 cm spectral range further confirms that the Watson-Crick isomer is preferentially produced (91%) at pH = 5.8, while the Hoogsteen isomer predominates (66%) at pH = 3.2). These fingerprint signatures are expected to be useful for the development of new analytical methodologies and to trigger isomer selective photochemical studies of protonated DNA base pairs.
使用电喷雾电离源从两种不同pH值（5.8和3.2）的溶液中产生气相质子化鸟嘌呤 - 胞嘧啶（CGH）对。串联质谱（MS/MS）碎裂模式和差分离子淌度谱（DIMS）的一致证据表明存在CGH对的两种异构体，其相对丰度强烈依赖于溶液的pH值。在900 - 1900 cm光谱范围内的气相红外多光子解离（IRMPD）光谱进一步证实，在pH = 5.8时优先产生沃森 - 克里克异构体（91%），而在pH = 3.2时霍格施泰因异构体占主导（66%）。预计这些指纹特征将有助于开发新的分析方法，并引发质子化DNA碱基对的异构体选择性光化学研究。
