Chen_2015_Biochem.J_466_243

Reference

Title : Kinetic characterization of a cocaine hydrolase engineered from mouse butyrylcholinesterase - Chen_2015_Biochem.J_466_243
Author(s) : Chen X , Huang X , Geng L , Xue L , Hou S , Zheng X , Brimijoin S , Zheng F , Zhan CG
Ref : Biochemical Journal , 466 :243 , 2015
Abstract :

Mouse butyrylcholinesterase (mBChE) and an mBChE-based cocaine hydrolase (mCocH, i.e. the A199S/S227A/S287G/A328W/Y332G mutant) have been characterized for their catalytic activities against cocaine, i.e. naturally occurring (-)-cocaine, in comparison with the corresponding human BChE (hBChE) and an hBChE-based cocaine hydrolase (hCocH, i.e. the A199S/F227A/S287G/A328W/Y332G mutant). It has been demonstrated that mCocH and hCocH have improved the catalytic efficiency of mBChE and hBChE against (-)-cocaine by ~8- and ~2000-fold respectively, although the catalytic efficiencies of mCocH and hCocH against other substrates, including acetylcholine (ACh) and butyrylthiocholine (BTC), are close to those of the corresponding wild-type enzymes mBChE and hBChE. According to the kinetic data, the catalytic efficiency (kcat/KM) of mBChE against (-)-cocaine is comparable with that of hBChE, but the catalytic efficiency of mCocH against (-)-cocaine is remarkably lower than that of hCocH by ~250-fold. The remarkable difference in the catalytic activity between mCocH and hCocH is consistent with the difference between the enzyme-(-)-cocaine binding modes obtained from molecular modelling. Further, both mBChE and hBChE demonstrated substrate activation for all of the examined substrates [(-)-cocaine, ACh and BTC] at high concentrations, whereas both mCocH and hCocH showed substrate inhibition for all three substrates at high concentrations. The amino-acid mutations have remarkably converted substrate activation of the enzymes into substrate inhibition, implying that the rate-determining step of the reaction in mCocH and hCocH might be different from that in mBChE and hBChE.

PubMedSearch : Chen_2015_Biochem.J_466_243
PubMedID: 25486543
Gene_locus related to this paper: human-BCHE

Citations formats

Chen X, Huang X, Geng L, Xue L, Hou S, Zheng X, Brimijoin S, Zheng F, Zhan CG (2015)
Kinetic characterization of a cocaine hydrolase engineered from mouse butyrylcholinesterase
Biochemical Journal 466 :243

Chen X, Huang X, Geng L, Xue L, Hou S, Zheng X, Brimijoin S, Zheng F, Zhan CG (2015)
Biochemical Journal 466 :243