Catalytic constants for ATCh hydrolysis by wild type and mutant human AChE in 0.1 m phosphate buffer, pH 7.4, at 22 °C
For all studied enzymes, inhibition by excess ATCh was evident except for F297I/Y337A and Y337A/F338A, where ATCh hydrolysis followed simple Michaelis kinetics (b = 1). Hydrolysis by F295L/Y337A/F338A was activated by excess substrate (b >1). kcat values for WT hAChE and mutants F338A and Y337A/F338A were determined as (1.4 ± 0.40)·105 min−1, (0.74 ± 0.21)·105 min−1, and (0.53 ± 0.09)·105 min−1, respectively.