A recently designed and discovered cocaine hydrolase (CocH), engineered from human butyrylcholinesterase, has been proven promising as a novel enzyme therapy for treatment of cocaine overdose and addiction because it is highly efficient in catalyzing hydrolysis of naturally occurring (−)-cocaine. It has been known that the CocH also has a high catalytic efficiency against (+)-cocaine, a synthetic enantiomer of cocaine. Reaction pathway and the corresponding free energy profile for the CocH-catalyzed hydrolysis of (+)-cocaine have been determined, in the present study, by performing first-principles pseudobond quantum mechanical/molecular mechanical free energy (QM/MM-FE) calculations. According to the QM/MM-FE results, the catalytic hydrolysis process is initiated by the nucleophilic attack on carbonyl carbon of (−)-cocaine benzoyl ester via hydroxyl oxygen of S198 side chain, and the second reaction step (i.e., dissociation of benzoyl ester) is rate-determining. This finding for CocH-catalyzed hydrolysis of (+)-cocaine is remarkably different from that for the (+)-cocaine hydrolysis catalyzed by bacterial cocaine esterase in which the first reaction step of the deacylation is associated with the highest free energy barrier (~17.9 kcal/mol). The overall free energy barrier (~16.0 kcal/mol) calculated for the acylation stage of CocH-catalyzed hydrolysis of (+)-cocaine is in good agreement with the experimental free energy barrier of ~14.5 kcal/mol derived from the experimental kinetic data.
|Number of pages||9|
|Journal||Theoretical Chemistry Accounts|
|State||Published - Jan 1 2016|
Bibliographical noteFunding Information:
This work was supported in part by the NIH (Grants R01 DA035552, R01 DA013930, R01 DA032910, and R01 DA025100), NSF (Grant CHE-1111761), and NSFC (Grant No. 21102050). The entire research was performed at the University of Kentucky. The authors acknowledge the Center for Computational Sciences (CCS) at University of Kentucky for supercomputing time on IBM X-series Cluster with 340 nodes or 1360 processors.
© 2015, Springer-Verlag Berlin Heidelberg.
- Catalytic mechanism
- Enzymatic hydrolysis
ASJC Scopus subject areas
- Physical and Theoretical Chemistry