TABLE 3.
Steady-state kinetic parameters of the β-lactamase PER-6 and comparison of parameter values obtained for β-lactamase PER-2 (23)a
| β-Lactam | PER-6 |
PER-2 |
||
|---|---|---|---|---|
| kcat (s−1) | Km (μM) | kcat/Km (mM−1·s−1) | kcat/Km (mM−1·s−1) | |
| Benzylpenicillin | 5 | 200 | 25 | 120 |
| Ampicillin | 1 | 20 | 50 | 330 |
| Ticarcillin | 0.4 | 9 | 50 | ND |
| Piperacillin | 0.1 | 4 | 25 | 200 |
| Cephalothin | 8 | 55 | 145 | 670 |
| Ceftazidime | 12 | 1,000 | 10 | 430 |
| Cefotaxime | 40 | 900 | 45 | 760 |
| Cefepime | 10 | 2,000 | 5 | 20 |
| Cefpirome | 12 | 1,500 | 8 | NA |
| Cefoxitin | ND | ND | ND | <10 |
| Aztreonam | 3 | 40 | 75 | 120 |
| Moxalactam | ND | ND | ND | NA |
| Imipenem | 0.006 | 1.5 | 4 | <10 |
| Meropenem | 0.004 | 10 | 0.4 | NA |
| Ertapenem | 0.002 | 7 | 0.3 | NA |
a
Data are means of results from three independent experiments. Standard deviations were within 10% of the means. ND, not determinable or no detectable hydrolysis (<0.01 s−1); NA, not available.