Table 2.
Reactivation of methamidophos- and fenamiphos-inhibited hAChE by selected oximes.
| Oxime | k2 (min−1) | KOX (mM) | kr (min−1 M−1) | Reactmax (%) |
|---|---|---|---|---|
| Methamidophos | ||||
| 1A | 2.9 ± 0.6 | 0.13 ± 0.06 | 22,400 ± 6,388 | 40 |
| 14A | 22.2 ± 3.8 | 0.20 ± 0.06 | 108,300 ± 17,090 | 85 |
| RS194B | 6.7 ± 0.9 | 0.17 ± 0.05 | 39,810 ± 7,479 | 100 |
| Obidoxime | 6.8 ± 2.3 | 0.09 ± 0.04 | 75,320 ± 10,210 | 70 |
| TMB-4 | 16.5 ± 6.6 | 0.14 ± 0.07 | 116,600 ± 12,380 | 80 |
| HI-6 | 1.2 ± 0.1 | 0.05 ± 0.009 | 27,140 ± 2,382 | 80 |
| 2-PAM | 2.7 ± 0.2 | 0.06 ± 0.006 | 42,190 ± 2,547 | 80 |
| Fenamiphos | ||||
| 1A | 0.016 ± 0.002 | 0.22 ± 0.06 | 72 ± 12 | 40 |
| 14A | 0.069 ± 0.034 | 0.81 ± 0.61 | 85.8 ± 24.8 | 45 |
| RS194B | 0.053 ± 0.019 | 2.45 ± 1.42 | 21.5 ± 4.6 | 45 |
| Obidoxime | 0.091 ± 0.026 | 1.51 ± 0.71 | 60.7 ± 12.1 | 65 |
| TMB-4 | 0.082 ± 0.010 | 0.61 ± 0.15 | 134.2 ± 17.6 | 65 |
| HI-6 | 0.006 ± 0.001 | 0.30 ± 0.09 | 20.3 ± 4.9 | 65 |
| 2-PAM | 0.003 ± 0.0002 | 0.35 ± 0.09 | 7.5 ± 1.5 | 70 |
Kinetic parameters (± SEM): the maximal first-order reactivation rate constant (k2), the dissociation constant of the phosphylated enzyme-oxime reversible complex (KOX), overall second-order reactivation rate constant (kr) and maximal percentage of reactivation (Reactmax) were determined from at least three experiments at 25 °C.