Stokes Sarah T, Li Xiang, Grubisic Andrej, Ko Yeon Jae, Bowen Kit H
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
J Chem Phys. 2007 Aug 28;127(8):084321. doi: 10.1063/1.2774985.
The nucleoside parent anions 2(')-deoxythymidine(-), 2(')-deoxycytidine(-), 2(')-deoxyadenosine(-), uridine(-), cytidine(-), adenosine(-), and guanosine(-) were generated in a novel source, employing a combination of infrared desorption, electron photoemission, and a gas jet expansion. Once mass selected, the anion photoelectron spectrum of each of these was recorded. In the three cases in which comparisons were possible, the vertical detachment energies and likely adiabatic electron affinities extracted from these spectra agreed well with the values calculated both by Richardson et al. [J. Am. Chem. Soc. 126, 4404 (2004)] and by Li et al. [Radiat. Res. 165, 721 (2006)]. Through the combination of our experimental results and their theoretical calculations, several implications emerge. (1) With the possible exception of dG(-), the parent anions of nucleosides exist, and they are stable. (2) These nucleoside anions are valence anions, and in most cases the negative charge is closely associated with the nucleobase moiety. (3) The nucleoside parent anions we have generated and studied are the negative ions of canonical, neutral nucleosides, similar to those found in DNA.
采用红外解吸、电子光发射和气体喷射膨胀相结合的方法，在一种新型源中产生了核苷母体阴离子2('-)-脱氧胸苷(-)、2('-)-脱氧胞苷(-)、2('-)-脱氧腺苷(-)、尿苷(-)、胞苷(-)、腺苷(-)和鸟苷(-)。一旦进行质量选择，就记录这些阴离子的光电子能谱。在三种可以进行比较的情况下，从这些光谱中提取的垂直脱附能和可能的绝热电子亲和能与理查森等人[《美国化学会志》126, 4404 (2004)]和李等人[《辐射研究》165, 721 (2006)]计算的值非常吻合。通过结合我们的实验结果和他们的理论计算，出现了几个结论。(1) 除了dG(-)可能例外，核苷的母体阴离子是存在的，并且它们是稳定的。(2) 这些核苷阴离子是价阴离子，并且在大多数情况下，负电荷与核碱基部分紧密相关。(3) 我们产生并研究的核苷母体阴离子是典型中性核苷的负离子，类似于在DNA中发现的那些。
