Predicted Michaelis-Menten complexes of cocaine-butyrylcholinesterase: Engineering effective butyrylcholinesterase mutants for cocaine detoxication

Hong Sun, Jamal El Yazal, Oksana Lockridge, Lawrence M. Schopfer, Stephen Brimijoin, Yuan Ping Pang

Research output: Contribution to journalArticle

77 Scopus citations

Abstract

Butyrylcholinesterase (BChE) is important in cocaine metabolism, but it hydrolyzes (-)-cocaine only one-two thousandth as fast as the unnatural (+)-stereoisomer. A starting point in engineering BChE mutants that rapidly clear cocaine from the bloodstream, for overdose treatment, is to elucidate structural factors underlying the stereochemical difference in catalysis. Here, we report two three-dimensional Michaelis-Menten complexes of BChE liganded with natural and unnatural cocaine molecules, respectively, that were derived from molecular modeling and supported by experimental studies. Such complexes revealed that the benzoic ester group of both cocaine stereoisomers must rotate toward the catalytic Ser198 for hydrolysis. Rotation of (-)-cocaine appears to be hindered by interactions of its phenyl ring with Phe 329 and Trp430. These interactions do not occur with (+)-cocaine. Because the rate of (-)-cocaine hydrolysis is predicted to be determined mainly by the re-orientation step, it should not be greatly influenced by pH. In fact, measured rates of this reaction were nearly constant over the pH range from 5.5 to 8.5, despite large rate changes in hydrolysis of (+)-cocaine. Our models can explain why BChE hydrolyzes (+)-cocaine faster than (-)-cocaine, and they suggest that mutations of certain residues in the catalytic site could greatly improve catalytic efficiency and the potential for detoxication.

Original languageEnglish (US)
Pages (from-to)9330-9336
Number of pages7
JournalJournal of Biological Chemistry
Volume276
Issue number12
DOIs
StatePublished - Mar 23 2001

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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