Chen E S, Chen E C, Sane N
Center for Research in Parallel Computing, Rice University, Houston, Texas 77005, USA.
Biochem Biophys Res Commun. 1998 May 8;246(1):228-30. doi: 10.1006/bbrc.1998.8584.
The major ion formed in Negative Ion Chemical Ionization Mass Spectrometry of Adenine, Guanine, Cytosine, Uracil and Thymine is the dehydrogenated anion. The CURES EC procedure for optimizing Austin Model-1 Multiconfigurational Configuration Interaction semi-empirical calculations is applied to the electron affinities of the corresponding dehydrogenated bases and N-H bond dissociation energies. These calculated values will be compared with literature values of the gas phase acidities of the purines and pyrimidines. The N-H bond dissociation energies are about 3.95 eV for Guanine, Adenine, and Thymine and 4.08 eV for Cytosine and Uracil. The electron affinities of the radicals are AMinH = 3.50 eV, GMinH = 3.46 eV, CMinH = 3.38 eV, UMinH = 3.48 eV, TMinH = 3.46 eV.
腺嘌呤、鸟嘌呤、胞嘧啶、尿嘧啶和胸腺嘧啶在负离子化学电离质谱中形成的主要离子是脱氢阴离子。用于优化奥斯汀模型 -1 多组态相互作用半经验计算的CURES EC程序应用于相应脱氢碱基的电子亲和能和N - H键解离能。这些计算值将与嘌呤和嘧啶气相酸度的文献值进行比较。鸟嘌呤、腺嘌呤和胸腺嘧啶的N - H键解离能约为3.95电子伏特，胞嘧啶和尿嘧啶的N - H键解离能为4.08电子伏特。自由基的电子亲和能为：AMinH = 3.50电子伏特，GMinH = 3.46电子伏特，CMinH = 3.38电子伏特，UMinH = 3.48电子伏特，TMinH = 3.46电子伏特。
