5-羟甲基胞嘧啶pKa值的理论研究

Theoretical Research on p Ka Value of the 5-Hydroxymethylcytosine

采用两种不同动力学循环方案,在B3LYP/6-311++G(d,p)+ZPE和B3LYP/aug-ccp VTZ//B3LYP/6-311++G(d,p)+ZPE水平上,同时考虑PCM和CPCM模型对5-羟甲基胞嘧啶(5-HMe Cyt)中N3、N4、O2不同位点质子化的p Ka值进行计算研究.结果表明:采用经验值法,5-HMe Cyt中N3位置质子化的p Ka值最大;采用质子交换法,以N3质子化的胞嘧啶为参考酸,发现CPCM模型计算结果对计算方法的依赖性较大.

The protonated pKa values in different positions of O2, N3, N4 for 5-hydroxymethylcytosine （5-HMeCyt） are calculated by adopting two different dynamic cycle schemes at the B3LYP/6-311 ＋ ＋ G（d, p） ＋ZPE and B3LYP/aug-cc-pVTZ//B3LYP/6-311 ＋ ＋G（d, p） ＋ ZPE level, which consider the effect of the PCM and CPCM models. The results show that the protonated pKa value is the largest in the N3 position of the 5-HMeCyt by the empirical value method. The results of CPCM model greatly depend on the calculation method when taking the N3 position of cytosine as reference by the proton exchange method.