Figure 5.

Kinetic data obtained in vitro for enzymatic hydrolysis of (−)-cocaine and cocaethylene: (A) wild-type human BChE; (B) E14-3; (C) E12-7. To minimize the possible systematic experimental errors of the kinetic data, each enzyme’s catalytic activities against both cocaethylene and (−)-cocaine were assayed at the same time under the same experimental conditions so as to reliably determine the kinetic parameters of the enzyme against cocaethylene relative to those against (−)-cocaine. The reaction rate (represented in μM min⁻¹ per nM enzyme) was determined by measuring the rate of the change of the absorbance at 230 nm.