利用量子化学方法研究了气相和水溶液下,氨基酸侧链与鸟嘌呤和胞嘧啶间的氢键作用.应用B3LYP/6-31+G( d,p)方法优化复合物几何结构,使用MP2/aug-cc-pVDZ方法进行复合物能量、自然键轨道( NBO)电荷和二阶稳定化能的计算.结果表明,水溶液可使氨基酸侧链与碱基或碱基对之间氢键键能显著减小；带电复合物气相和水溶液氢键键能之差范围为50.63~146.48 kJ/mol,中性为0.17~24.94 kJ/mol；电荷的转移量与氢键键能成正比,电荷转移量越多,复合物越稳定；二阶稳定化能与氢键键长成反比,与电荷转移量成正比,且气相与水溶液氢键二阶稳定化能之比约为两相的电荷转移量之比.水溶液对该类体系中氢键作用具有明显影响.%Quantum chemical method was employed to study the hydrogen bond interaction between the amino acid side chain( AASC) analogues and G, C bases, as well as GC base pair in gas and aqueous solution. B3LYP/6-31+G(d,p) was carried out to optimize the complex structures. Moreover, MP2/aug-cc-pVDZ was performed to calculate the energies, natural bond orbital ( NBO ) charges and second order stabilization energies of these complexes. It demonstrates that hydrogen bond interaction between AASC analogues and bases or base pair can be dramatically weakened in aqueous solution, compared with in gas. For the complexes of AASC analogues with positive charge along with the base or base pair, the difference of their hydrogen bond energies between in gas and aqueous solution is 50. 63—146. 48 kJ/mol, whereas 0. 17—24. 94 kJ/mol for neutral AASC analogues. The value of charge transfer is proportional to the hydrogen bonding energy, the more the charge transfer, the more stable the complex. The second-order stabilization energies are inverse proportional to the hydrogen bonds, and the second-order stabilization energies of gas divide ones of aqueous solution is approximately to the value of charge transfer in two phases. It is explicitly shown that aqueous solution has an extremely large impact on hydrogen bonding in these systems.
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