Most Efficient Cocaine Hydrolase Designed by Virtual Screening of Transition States

Abstract

Abstract:Cocaine is recognized as the most reinforcing of all drugs of abuse. There is no anticocaine medication available. The disastrous medical and social consequences of cocaine addiction have made the development of an anticocaine medication a high priority. It has been recognized that an ideal anticocaine medication is one that accelerates cocaine metabolism producing biologically inactive metabolites via a route similar to the primary cocaine-metabolizing pathway, i.e., cocaine hydrolysis catalyzed by plasma enzyme butyrylcholinesterase (BChE). However, wild-type BChE has a low catalytic efficiency against the abused cocaine. Design of a high-activity enzyme mutant is extremely challenging, particularly when the chemical reaction process is rate-determining for the enzymatic reaction. Here we report the design and discovery of a high-activity mutant of human BChE by using a novel, systematic computational design approach based on transition-state simulations and activation energy calculations. The novel computational design approach has led to discovery of the most efficient cocaine hydrolase, i.e., a human BChE mutant with an ∼2000-fold improved catalytic efficiency, promising for therapeutic treatment of cocaine overdose and addiction as an exogenous enzyme in human. The encouraging discovery resulted from the computational design not only provides a promising anticocaine medication but also demonstrates that the novel, generally applicable computational design approach is promising for rational enzyme redesign and drug discovery.

Long-Term Reduction of Cocaine Self-Administration in Rats Treated with Adenoviral Vector-Delivered Cocaine Hydrolase: Evidence for Enzymatic Activity

“…This study examined a potentially successful therapy involving long-term gene transfer of an enzyme that rapidly hydrolyzes cocaine to inactive metabolites. The enzyme, a 'cocaine hydrolase' (CocH) derived by multiple mutations of human butyrylcholinesterase (BChE; Zheng et al, 2008;Xue et al, 2013), is expected to reduce drug access to brain. If CocH were sustained at adequate levels, it might aid users who desire to become abstinent.…”

Long-Lasting Effects of a PEGylated Mutant Cocaine Esterase (CocE) on the Reinforcing and Discriminative Stimulus Effects of Cocaine in Rats

“…In an attempt to improve upon BChE's catalytic efficiency, Zhan and colleagues have used site-directed mutagenesis to create mutant BChEs capable of hydrolyzing cocaine B450-2000 times more efficiently than native BChE (Pan et al, 2005;Zheng et al, 2008). These mutant BChEs have shown promising results when evaluated in rodents, effectively reducing the cardiovascular, lethal, and response-reinstating effects of cocaine (Brimijoin et al, 2008;Xue et al, 2010;Zheng et al, 2008). In addition, an albumin-fused mutant BChE (Albu-CocH) has been shown to decrease progressive ratio responding for cocaine (Carroll et al, 2011), suggesting that it is also capable of reducing the reinforcing effectiveness of cocaine.…”

Molecular Modeling in Enzyme Design, Toward In Silico Guided Directed Evolution

“…In this line, we expect the development of additional techniques combining quick bioinformatics (or knowledge-based) screening of a large sequence space, with a molecular modeling refinement of selected mutants. This last step could be further hierarchically broken down into a first classical molecular modeling screening followed by selected quantum chemical reevaluations, in a similar manner to the previously described study by Zheng et al [181]. Even though computational techniques are becoming more precise and easy to implement, a synergic effort between in silico predictions and experimental validation will be, in our opinion, the preferred solution.…”

“…QM/MM schemes, which have been widely applied to elucidate enzymatic reaction mechanisms [180], have been employed to rescore promising candidates [156,180]. A remarkable example is the hierarchical approach of Zheng et al used to design a cocaine hydrolase [181]. Firstly, the reaction coordinate and the TS of the rate-determining limiting step are determined in the wild type.…”