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用密度泛函理论在B3LYP/6-311G(d,p)水平上研究了甲醇和氨辅助的腺嘌呤水解脱氨机理,结果表明该反应首先是在水的亲核进攻下形成一个四面体结构中间体,然后该中间体通过构象变化得到两个不同构象,从而找到两条不同反应路径.在路径a中,辅助分子参与了过渡态的形成,起到转移氢原子的作用;而在路径b中,辅助分子仅作为介质,没有参与过渡态的形成.在氨辅助的情况下,腺嘌呤在亲核反应前发生了胺-亚胺异构化,而在甲醇辅助机理中则未发生该异构化.能量结果表明甲醇辅助腺嘌呤脱氨反应具有与水辅助类似的势垒,而氨辅助反应的势垒则比水辅助的高.
The mechanism of methanolysis and ammonia-assisted adenine hydrolysis and deamination was studied at the B3LYP / 6-311G (d, p) level using density functional theory. The results show that the reaction firstly forms a tetrahedral structure under the nucleophilic attack of water Intermediates, and then the intermediate can be obtained by the conformational changes of two different conformations, to find two different reaction path.In the path a, the auxiliary molecules involved in the formation of transition state, play the role of hydrogen atoms transfer; and in the path b , The accessory molecule only serves as a mediator and does not participate in the formation of the transition state.In the case of ammonia-assisted, adenine undergoes amine-imine isomerization prior to the nucleophilic reaction and does not occur in the methanol-assisted mechanism The energy results show that the methanol-assisted adenine deamination reaction has a barrier similar to that of water-assist, whereas the ammonia-assisted reaction has a higher barrier than the water-assist.