TABLE 2.
Kinetic parameters of the purified β-lactamase CGA-1a
| β-Lactam | kcat (s−1) | Km (μM) | kcat/Km (mM−1 · s−1) |
|---|---|---|---|
| Benzylpenicillin | 20 | 4 | 5,500 |
| Amoxicillin | 20 | 26 | 800 |
| Ticarcillin | 0.2 | <1 | >0.2 |
| Piperacillin | <0.01 | ND | ND |
| Cefalothin | 30 | 6 | 4,500 |
| Cephaloridine | 20 | 17 | 1,200 |
| Cefuroxime | 70 | 31 | 2,200 |
| Cefoperazone | 10 | 3 | 2,000 |
| Ceftriaxone | 35 | 19 | 1,800 |
| Ceftazidime | 70 | 360 | 200 |
| Cefotaxime | 60 | 52 | 1,100 |
| Cefepime | 10 | 96 | 100 |
| Cefpirome | 10 | 23 | 450 |
| Cefoxitin | <0.002 | ND | ND |
| Moxalactam | <0.002 | ND | ND |
| Imipenem | 0.5 | 3 | 120 |
| Aztreonam | 0.5 | 6 | 60 |
a
Values are geometric means of three independent measures (standard deviations were within 15%). ND, not detectable activity.