Table 1.
Enthalpy (ΔH) and rate (kOH) changes for the alkaline hydrolysis of phenyl acetate, dihydrocoumarin, and paraoxon. kOH is the second-order rate constant for the hydroxide ion reaction with the carbonyl groups of various substrates. kcat, KM and kcat/KM are the turnover number, the Michaelis constant and catalytic efficiency, respectively. a [35]; b [19]; c [36,37].
| Substrate | ΔH (kJ/mol) | kOH (M−1 s−1) | kcat (s−1) | KM (mM) | kcat/KM (M−1 s−1) |
|---|---|---|---|---|---|
| phenyl acetate | −97 a | 1.3 a | 700 b | 1.2 b | 580,000 |
| dihydrocoumarin | −105 a | 824 a | 150 b | 0.13 b | 1,150,000 |
| paraoxon | n.d. | 0.075 c | 4.8 b | 0.8 b | 6000 |