Extensive computational modeling and simulations have been carried out, in the present study, to uncover the fundamental reaction pathway for butyrylcholinesterase (BChE)-catalyzed hydrolysis of ghrelin, demonstrating that the acylation process of BChE-catalyzed hydrolysis of ghrelin follows an unprecedented single-step reaction pathway and the single-step acylation process is rate-determining. The free energy barrier (18.8 kcal/mol) calculated for the rate-determining step is reasonably close to the experimentally-derived free energy barrier (~19.4 kcal/mol), suggesting that the obtained mechanistic insights are reasonable. The single-step reaction pathway for the acylation is remarkably different from the well-known two-step acylation reaction pathway for numerous ester hydrolysis reactions catalyzed by a serine esterase. This is the first time demonstrating that a single-step reaction pathway is possible for an ester hydrolysis reaction catalyzed by a serine esterase and, therefore, one no longer can simply assume that the acylation process must follow the well-known two-step reaction pathway.
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This work was supported in part by the National Institutes of Health (NIH) through the NIDA Translational Avant-Garde Award (UH2 DA041115) and R01 grants (R01 DA035552, R01 DA032910, R01 DA013930, and R01 DA025100) to CGZ and the National Science Foundation (NSF) through grant CHE-1111761 to CGZ.
Yao, Jianzhuang; Yuan, Yaxia; Zheng, Fang; and Zhan, Chang-Guo, "Unexpected Reaction Pathway for Butyrylcholinesterase-Catalyzed Inactivation of "Hunger Hormone" Ghrelin" (2016). Molecular Modeling and Biopharmaceutical Center Faculty Publications. 1.