TABLE 2.
Kinetic parameters of the efflux process
| Substrate |
 (nmol/mg/s) |
Hill coefficient | K0.5 (μM) | Permeability coefficient (μm/s) | Substituent log Pa |
|---|---|---|---|---|---|
| Dicloxacillin | 0.98, 0.95, 0.94 | 3.6, 4.7, 4.3 | 0.53, 0.83, 0.82 | 0.6, 0.6, 0.6 | 3.4 |
| Cloxacillin | 0.89, 0.99, 0.80 | 2.3, 2.7, 2.4 | 0.95, 1.03, 0.91 | 0.6, 0.6, 0.6 | 2.8 |
| Oxacillin | 0.94, 1.1, 0.94 | 2.6, 2.7, 2.6 | 1.04, 0.97, 1.03 | 0.6, 0.6, 0.6 | 2.1 |
| Azlocillin | 0.42, 0.41, 0.35 | 4.0, 4.0, 4.6 | 1.08, 1.06, 1.09 | 0.4, 0.4, 0.4 | 0.71 |
| Mezlocillin | 0.51, 0.47, 0.50 | 4.4, 4.5, 4.5 | 1.09, 1.08, 1.11 | 0.5, 0.5, 0.5 | 0.67 |
| Piperacillin | 0.39, 0.35, 0.39 | 4.1, 3.7, 4.1 | 1.06, 1.08, 1.08 | 0.4, 0.4, 0.3 | 0.45 |
| Penicillin V | 0.72, 0.85, 0.72 | 4.7, 4.7, 4.6 | 0.82, 0.84, 0.83 | 0.8, 0.7, 0.7 | 1.54 |
| Ampicillin | 0.38, 0.37, 0.37 | 1.9, 2.3, 2.5 | 0.88, 0.92, 1.03 | 0.8, 0.8, 0.8 | −1.03 |
a
The log P values of the 6-substituent were calculated after the carboxyl group was changed to a methyl group at the website http://www.molinspiration.com/services/lopP.html.