【模拟佳文二】JACS 静电导向动力学分析萜烯合成酶
Electrostatically Guided Dynamics—The Root of Fidelity in a Promiscuous Terpene Synthase?http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/0/jacsat.ahead-of-print/ja308295p/aop/images/medium/ja-2012-08295p_0011.gif
Terpene cyclases are responsible for the initial cyclization cascade in the multistep synthesis of more than 60 000 known natural products. This abundance of compounds is generated using a very limited pool of substrates based on linear isoprenoids. The astounding chemodiversity obtained by terpene cyclases suggests a tremendous catalytic challenge to these often promiscuous enzymes. In the current study we present a detailed mechanistic view of the biosynthesis of the monoterpene bornyl diphosphate (BPP) from geranyl diphosphate by BPP synthase using state of the art simulation methods. We identify the bornyl cation as an enzyme-induced bifurcation point on the multidimensional free energy surface, connecting between the product BPP and the side product camphene. Chemical dynamics simulations suggest that the active site diphosphate moiety steers reaction trajectories toward product formation. Nonetheless, chemical dynamics is not precise enough for exclusive product formation, providing a rationale for the lack of fidelity in this promiscuous terpene cyclase.
Gas-Phase Modeling：All gas-phase calculations were performed with the Gaussian 09 program.
All QM(M06-2X)/MM simulations used the CHARMM simulation platform interfaced with the Q-CHEM program。
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