Mechanistic Insights into Protonated Diamines-catalyzed Decarboxylation of Oxaloacetate
Mechanistic Insights into Protonated Diamines-catalyzed Decarboxylation of Oxaloacetate
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DOI：
10.2174/1570178615666181003133432
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发表时间：
2019-02
影响因子：
0.8
通讯作者：
Chuan-gang Fan;Ming-zhi Song
中科院分区：
文献类型：
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作者：
Chuan-gang Fan;Ming-zhi Song
用密度泛函理论研究了水溶液中质子化二胺催化草酰乙酸阴离子脱羧反应的化学机理。计算结果表明，OA 2-的脱羧反应活化吉布斯自由能最高，质子化乙二胺（ENH+）是5种二胺中最好的催化剂，这与Thalji等人的研究结果一致;而OA 2-的脱水反应除1，3-丙二胺外，其它步骤都是速率控制步骤。质子化1，4-丁二胺是最好的催化剂。第二个氨基作为质子受体或质子供体参与反应，通过氢键参与脱羧反应，降低了整个催化过程的活性吉布斯自由能垒。这些结果提供了深入了解几种酶的精确催化机制，已知这些酶的反应通过亚胺中间体进行。
The chemical mechanisms of protonated diamines-catalyzed decarboxylation of oxaloacetic acid anions in water solutions have been studied by using density functional theory. The calculated results show that the activated Gibbs free energy of the decarboxylation step is the highest in the whole diamine-catalytic processes for OA2-, and protonated ethylenediamine (ENH+) is the best catalyst of the five diamines, which is consistent with the study of Thalji et al. However, for OA-, different with OA2-, the dehydration step is the rate-determining one except 1,3-diaminopropane, and protonated 1,4- diaminobutane is the best catalyst of the five catalysts. The results also indicate that the second amino group participates in the reaction as the proton acceptor or proton donor, and it assists in decarboxylation by hydrogen bonds, decreasing the active Gibbs free energy barrier of the whole catalytic process. These results provide insight into the precise catalytic mechanism of several enzymes whose reactions are known to proceed via an imine intermediate.