5,10-CH^+-THF简化模型转移一碳单元反应机理的计算研究

Theoretical Study on the Mechanism of One Carbon Unit Transfer in 5,10-CH^+-THF Model

生物体内嘌呤、嘧啶、胸苷酸等的合成以及细胞的代谢过程都伴随有一碳单元转移反应。在这类反应中,四氢叶酸是一碳单元的载体同时又是甲基化的直接甲基元。选择四氢叶酸的模型化合物与邻苯二胺的反应作为研究对象,从理论上研究了一碳单元的转移过程,探讨了该反应的反应过程、反应机理和能量变化。研究发现四氢叶酸模型化合物与邻苯二胺依次经过质子转移、键断裂、新键的形成、质子转移以及二胺基的消除等多个步骤,完成了一碳单元转移反应。由能量变化可以得出一碳单元转移过程中质子转移为限速步骤,与实验上所得结论一致。得到了比较详细的一碳单元转移机理。

The synthesis processes of purine, pyrimidine, and thymidylic acid in organism and the metabolism processes of cells are always accompanied by one carbon unit transfer reaction. In these one carbon unit transfer reactions the tetrahydrofolate is the carrier of one carbon unit and is the direct methyl unit of methylation at the same time. The reaction between the tetrahydrofolate model compounds and 1,2-diaminobenzene was chosen as model system, the reaction mechanism and energy variation of one carbon unit transfer process were studied theoretically. It was found by calculation that the reaction of the tetrahydrofolate model compounds with 1,2-diaminobenzene experience proton transfer, bond rupture, new bond formation, proton transfer and elim- ination of diamine to complete the transfer of one carbon unit from 1,2-diaminobenzene to model compounds. Of all the steps, the proton transfer was the rate-limiting step, which was consisted with the experimental result.