Abstract
It is known that the majority of cocaine users also consume alcohol. Alcohol can react with cocaine to produce a significantly more cytotoxic compound, cocaethylene. Hence a truly valuable cocaine-metabolizing enzyme as treatment for cocaine abuse/overdose should be efficient for not only cocaine itself, but also cocaethylene. The catalytic parameters (κcat and KM) of human BChE (butyrylcholinesterase) and two mutants (known as cocaine hydrolases E14-3 and E12-7) for cocaethylene are characterized in the present study, for the first time, in comparison with those for cocaine. On the basis of the obtained kinetic data, wild-type human BChE has a lower catalytic activity for cocaethylene (κcat =3.3 min-1, K M =7.5 μM and κcat/KM =4.40×105 M-1 min-1) compared with its catalytic activity for (-)-cocaine. E14-3 and E12-7 have a considerably improved catalytic activity against cocaethylene compared with the wild-type BChE. E12-7 is identified as the most efficient enzyme for hydrolysing cocaethylene in addition to its high activity for (-)-cocaine. E12-7 has an 861-fold improved catalytic efficiency for cocaethylene (κcat =3600 min-1, KM =9.5 μM and κcat/KM =3.79×108 M-1 min-1). It has been demonstrated that E12-7 as an exogenous enzyme can indeed rapidlymetabolize cocaethylene in rats. Further kinetic modelling has suggested that E12-7 with an identical concentration as that of the endogenous BChE in human plasma can effectively eliminate (-)-cocaine, cocaethylene and norcocaine in simplified kinetic models of cocaine abuse and overdose associated with the concurrent use of cocaine and alcohol.
Original language | English |
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Pages (from-to) | 447-457 |
Number of pages | 11 |
Journal | Biochemical Journal |
Volume | 460 |
Issue number | 3 |
DOIs | |
State | Published - Jun 15 2014 |
Keywords
- Butyrylcholinesterase
- Drug abuse
- Hydrolysis
- Kinetics
- Protein drug
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology