TABLE 5.
Kinetic parameters of the ATPase activities of wt Cdr1 and milbemycin α25-resistant Cdr1 mutants
| Strain | Km (mM) | Vmax (nmol/min/mg) | kcata (s−1) | kcat/Km (s−1mM−1) |
|---|---|---|---|---|
| CDR1 | 0.62 ± 0.04 | 303 ± 10 | 8.6 ± 0.27 | 13.9 ± 0.8 |
| G521R | 0.92 ± 0.06 | 497 ± 61 | 14.1 ± 1.72 | 15.4 ± 2.2 |
| M639I | 0.69 ± 0.12 | 233 ± 38 | 6.6 ± 1.07 | 9.7 ± 1.5 |
| A713P | 0.35 ± 0.03 | 101 ± 2 | 2.9 ± 0.04 | 8.3 ± 0.7 |
| T1355N | 0.58 ± 0.08 | 189 ± 20 | 5.4 ± 0.65 | 9.3 ± 1.3 |
a
To calculate enzyme turnover rates (kcat) and enzyme efficiencies (kcat/Km), we assumed that 10% of the plasma membrane protein was Cdr1 (MW of 169,941 Da). The values presented are the means (± SD) of at least three independent experiments.