取代基对腺嘌呤与胸腺嘧啶氢键复合物体系结合能的影响

Effects of Substituents on the Binding Energy in Hydrogen-bonded Complexes Containing Adenine and Thymine

优化得到了17个取代胸腺嘧啶与腺嘌呤形成的氢键复合物的结构,并计算了这些复合物的结合能,探讨了胸腺嘧啶上不同取代基对结合能的影响.结果表明,CF3取代的胸腺嘧啶与腺嘌呤间的结合能大于胸腺嘧啶与腺嘌呤间的结合能,这可能是屈氟尿苷具有阻止病毒及肿瘤扩散功能的原因所在.SO3H,CN和NO2取代的胸腺嘧啶与腺嘌呤间具有更大的结合能,表明这3个基团取代的胸腺嘧啶也可能具有潜在的抗肿瘤作用.分子中原子理论与自然键轨道分析表明,在所有体系中,氢键N—H…N最强,N—H…O C次之,C—H…O C最弱,轨道作用在氢键作用中占有重要地位.

The optimal structures and binding energies of seventeen substitutional thymine and adenine hydro- gen-bonded complexes were obtained theoretically and the effects of substituents on the binding energies were explored. The calculation results show that the interaction between trifluridine and adenine is stronger than that between thymine and adenine. This conclusion is in agreement with the fact that the association of trifluridine and adenine has precedence over the association of thymine and adenine. Compared with CF3 , three stronger electron withdrawing groups（ SO3 H, CN and NO2 ） can increase the binding energy between thymine and ade- nine, suggesting that the thymine substituted by these three groups may also provide a potential anticancer ap- plication. Atoms in molecules theory and the natural bond orbital analysis indicate that N--H-.. N hydrogen bon-ding is the strongest, N--H...O = C is stronger, while C--H…O = C is the weakest. Atoms in mole- cules theory and the natural bond orbital analysis also indicate that the orbital overlap interactions play a signi- ficant role in these hydrogen bonds.