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首页> 外文期刊>ACS catalysis >Protonation-Dependent Diphosphate Cleavage in FPP Cyclases and Synthases
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Protonation-Dependent Diphosphate Cleavage in FPP Cyclases and Synthases

机译：FPP环化酶和合酶中依赖质子化的二磷酸酯裂解。

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摘要

The cleavage of the magnesium-assisted diphosphate group (the PPi group) is one significant and prevalent rate-limiting step triggering the enzyme catalysis synthesis of terpenoid natural products. However, the PPi cleavage procedure has been rarely studied in most theoretical research of the terpenoid biosynthetic mechanism. In this work, QM(DFT)/MM MD simulations were employed to illuminate the detailed PPi cleavage mechanism in three different enzyme systems (ATAS, TEAS, and FPPS). We found that the most rational protonation state of the PPi group is highly dependent on the Mg2+ coordination modes and the enzyme classes. The deprotonation of PPi is favorable for triggering the catalysis reaction in ATAS, while monoprotonation in FPPS and biprotonation in TEAS are advantageous. As a result, similar PPi cleavage occurs by means of nucleophilic substitution reactions in TEAS/FPPS/ATAS but presents an S(N)1, S(N)2, and borderline mechanism, respectively. Finally, the alternative functions of PPi protonation and Mg2+ coordination modes are discussed.
机译：镁辅助二磷酸基团（PPi基团）的裂解是触发萜类天然产物的酶催化合成的重要且普遍的限速步骤。然而，在关于萜类生物合成机理的大多数理论研究中，很少研究PPi裂解过程。在这项工作中，QM（DFT）/ MM MD模拟被用来阐明三种不同酶系统（ATAS，TEAS和FPPS）中详细的PPi裂解机理。我们发现，PPi基团最合理的质子化状态高度依赖于Mg2 +配位模式和酶类别。 PPi的去质子化有利于引发ATAS中的催化反应，而FPPS中的单质子化和TEAS中的双质子化是有利的。结果，类似的PPi裂解通过TEAS / FPPS / ATAS中的亲核取代反应发生，但分别呈现S（N）1，S（N）2和临界机制。最后，讨论了PPi质子化和Mg2 +配位模式的替代功能。

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