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本文用计算化学的方法研究了有单个水分子参与的8-氧-2’-去氧鸟嘌呤核苷(8-oxodG)的N-糖苷键水解反应机理.研究结果表明,水分子有两个进攻方向,即水分子可以从去氧核糖糖环的上方和下方进攻C1’并且8-氧鸟嘌呤碱基的O8原子和N9原子都可以摘取去氧糖环的Ha2’.因此,8-oxodG与单个水分子作用的水解反应有四条不同的反应通道,且每条反应通道都包括两步,都形成类双氢呋喃中间体.O8原子摘取去氧糖糖环Ha2’的反应的两条反应途径的第一步的活化能相近,约为41.98kcal/mol;而N9原子摘取去氧糖糖环Ha2’的反应的两条反应途径的第一步的活化能也相近,约为47.31kcal/mol.碱基上O8原子摘取去氧核糖糖环Ha2’的反应的两条反应途径更具有优势.
In this paper, the mechanism of N-glycosidic hydrolysis of 8-oxo-2’-deoxyguanosine (8-oxodG) with a single water molecule has been studied by computational chemistry.The results show that there are two Offensive direction, that is, water molecules can attack Cl ’from above and below the deoxyribose ring, and both O8 and N9 atoms of the 8-oxoguanine base can be taken off Ha2’ of the deoxy sugar ring. Thus, 8- The hydrolysis of oxodG with a single water molecule has four different reaction channels, and each of the reaction channels includes two steps, forming a class of tetrahydrofuran intermediates.O8 atom removal deoxy sugar ring Ha2 ’reaction of two The activation energy of the first step of the reaction pathway is approximately 41.98 kcal / mol. The activation energies of the first reaction of the two reaction pathways for the N9 atom removal reaction of the deoxy sugar sugar ring Ha2 ’are also similar 47.31 kcal / mol. The two reaction pathways for the reaction of the O8 atom on the deoxyribose sugar ring Ha2 ’are more advantageous.