TABLE 2.
Kinetic parameters of the wild-type CphA and CphA4 and CphA5 enzymesa
| Substrate | CphA |
CphA4 |
CphA5 |
kcat/Km ratio for CphA5/CphA4 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Km (μM) | kcat (s−1) | kcat/Km (μM s−1) | Km (μM) | kcat (s−1) | kcat/Km (μM s−1) | Km (μM) | kcat (s−1) | kcat/Km (μM s−1) | ||
| Imipenem | 110 | 460 | 4.18 | 209 ± 4 | 28 | 0.13 | 453 ± 8 | 1,112 | 2.45 | 18.8 |
| Meropenem | 1,600 | 3,100 | 1.94 | 314 ± 6 | 38 | 0.12 | 374 ± 5 | 27 | 0.07 | 0.58 |
| Ertapenem | 230 | 700 | 3.04 | 688 ± 12 | 250 | 0.36 | 569 ± 15 | 2,963 | 5.21 | 14.5 |
| Biapenem | 1,700 | 120 | 0.07 | 870 ± 50 | 17 | 0.019 | >3,000 | 1,645 | NDb | ND |
a
Each kinetic value is the mean of five different measurements, with an error of <5%. Plus/minus values indicate the range from the five measurements.
b
ND, not determined.