槲皮素与腺嘌呤氢键作用的最佳位点

Site-preference of Quercetin Hydrogen Bonding to Adenine

本文优化得到了16个由槲皮素与腺嘌呤形成的氢键复合物的稳定结构,并计算了它们的结合能.研究发现,在气相和水相中,槲皮素均通过qu1位点与腺嘌呤作用形成稳定的氢键复合物.比较了腺嘌呤与槲皮素形成的氢键复合物、腺嘌呤与胸腺嘧啶形成的Watson-Crick碱基对的相对稳定性.在气相条件下Watson-Crick碱基对更稳定,在水相条件下腺嘌呤与槲皮素形成的氢键复合物更稳定,说明水相条件下腺嘌呤与槲皮素之间的相互作用强于与胸腺嘧啶之间的相互作用.基于标准反应Gibbs自由能变的计算结果估算了水相条件下腺嘌呤与槲皮素形成的氢键复合物和Watson-Crick碱基对的相对平衡浓度.

Sixteen stable hydrogen-bonded quercetin-adenine complexes were located at the B3 LYP /6-31 ＋G（d,p） level.The binding energies in gas phase were evaluated at the MP2 /6-311＋＋G（d,p） level with the basis set superposition error correction.The binding energies in water solvent were obtained at the MP2 /6-311＋＋ G（d,p） level with PCM model.The calculation results indicate that no matter in gas phase or water solvent,the hydrogen-bonded complexes formed through the quercetin site qu1 are the most stable.The relative stability of the hydrogen-bonded quercetin-adenine complexes and the thymine-adenine Waston-Crick base pair was further explored.The calculation results show that the base pair is more stable in gas phase whereas the hydrogen-bonded quercetin-adenine complexes are more stable in water solvent.Based on the calculation results of the standard Gibbs free energy change,the relative equilibrium concentrations between the hydrogenbonded quercetin-adenine complexes and the base pair in water solvent were estimated.