【摘要】 采用B3LYP/6-31+G(d,p)方法优化得到18个由组氨酸(His)/天冬酰胺(Asp)侧链分别与2种Watson-Crick碱基对(AT/GC)形成稳定构型.对18个稳定构型使用M06-2X-D3/aug-cc-pVDZ方法计算得到氢键复合物的结合能.在此基础上,采用同样的量子化学计算方法加上极化连续介质(PCM)模型计算得到氢键复合物在水相中的结合能.结果表明,碱基对AT与组氨酸侧链/天冬酰胺侧链氢键作用的较稳定作用位点是site 1与site 3;碱基对GC的较稳定作用位点是site 1与site 4.分子中原子(AIM)与自然键轨道(NBO)分析计算所得的结果与结合能强弱顺序一致.更多还原

【Abstract】 The optimal structures of eighteen hydrogen-bonded complexes,containing asparagine,histidine side chains and two Watson-Crick bases,were obtained at the B3 LYP/6-31+ G(d,p)level.The binding energies of the 18 stable hydrogen-bonded complexes were calculated using the M06-2 XD3/aug-cc-pVDZ method.On this basis,the stable structures and interaction energies of hydrogenbonded complexes in aqueous phase were calculated by using the same quantum chemistry calculation level and polarized continuum(PCM)model.The results showed that the stable sites of hydrogen bonding between Watson-Crick bases AT and asparagine and histidine side chains are site1 and site3;the stable sites of hydrogen bonding between Watson-Crick bases GC and asparagine and histidine are site1 and site4.The order of stability of the hydrogen-bonded complexes calculated from the analysis of atoms in molecules(AIM)and natural bond orbital(NBO)is consistent with the order of stability obtained from the binding energies.更多还原