Design, preparation, and characterization of high-activity mutants of human butyrylcholinesterase specific for detoxification of cocaine.
Cocaine is a widely abused drug without a U.S. Food and Drug Administration-approved medication. There is a recognized, promising anticocaine medication to accelerate cocaine metabolism, producing biologically inactive metabolites via a route similar to the primary cocaine-metabolizing pathway [i.e., cocaine hydrolysis catalyzed by butyrylcholinesterase (BChE) in plasma]. An ideal, therapeutically valuable mutant of human BChE should have not only a significantly improved catalytic activity against (-)-cocaine but also certain selectivity for (-)-cocaine over neurotransmitter acetylcholine (ACh), such that one would not expect systemic administration of the BChE mutant to interrupt cholinergic transmission. The present study accounting for the mutation-caused changes of the catalytic activities of BChE against both (-)-cocaine and ACh by means of molecular modeling and site-directed mutagenesis has led to identification of three BChE mutants that have not only a considerably improved catalytic efficiency against (-)-cocaine but also the desirable selectivity for (-)-cocaine over ACh. Two representative BChE mutants have been confirmed to be potent in actual protection of mice from acute toxicity (convulsion and lethality) of a lethal dose of cocaine (180 mg/kg). Pretreatment with the BChE mutant (i.e., 1 min before cocaine administration) dose-dependently protected mice against cocaine-induced convulsions and lethality. In particular, all mice pretreated with the mutant (e.g., 0.02 mg or more of A199S/F227A/S287G/A328W/E441D BChE) survived. The in vivo data reveal the primary factor (i.e., the relative catalytic efficiency), determining the efficacy in practical protection of mice from the acute cocaine toxicity and future direction for further improving the efficacy of the enzyme in the cocaine overdose treatment.
Xue
Liu
L
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street Lexington, KY 40536, USA.
Ko
Mei-Chuan
MC
Tong
Min
M
Yang
Wenchao
W
Hou
Shurong
S
Fang
Lei
L
Liu
Junjun
J
Zheng
Fang
F
Woods
James H
JH
Tai
Hsin-Hsiung
HH
Zhan
Chang-Guo
CG
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002091:Butyrylcholinesterase / Q000235:genetics / Q000378:metabolism*; D003042:Cocaine / Q000493:pharmacokinetics* / Q000633:toxicity; D006801:Humans; D006860:Hydrogen Bonding; D008658:Inactivation, Metabolic; D008297:Male; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D002091:Butyrylcholinesterase; D003042:Cocaine; D000109:Acetylcholine