TABLE 2.
Kinetic parameters of EBR-1 from E. coli BL21(DE3) compared with those of IND-2 from C. indologenes CIP 101026 (5), BlaB from C. meningosepticum CIP 6058 (32), and GOB-1 from C. meningosepticum PINT (1)d
| β-Lactam | EBR-1 parameters
|
kcat/Km (s−1 · mM−1)
|
||||
|---|---|---|---|---|---|---|
| kcat (s−1) | Km (μM) | kcat/Km (s−1 · mM−1) | IND-2 | BlaB | GOB-1 | |
| Benzylpenicillin | 115 | 47 | 2,500 | 4,600 | 8,800 | 1,900 |
| Amoxicillin | 640 | 690 | 900 | 700 | —a | 350 |
| Ticarcillin | 226 | 300 | 750 | — | — | 520 |
| Piperacillin | 410 | 490 | 850 | 2,000 | — | 1,700 |
| Cephalothin | 6 | 31 | 200 | 1,200 | — | 700 |
| Cephaloridine | 2 | 440 | 5 | — | 480 | — |
| Cefuroxime | 0.5 | 1b | 350 | — | — | 1,000 |
| Ceftriaxone | 3 | 7.5b | 400 | — | — | — |
| Ceftazidime | >2.5 | >1,000 | 2 | 5 | — | 800 |
| Cefotaxime | 1 | 50 | 20 | 900 | 220 | 850 |
| Cefepime | <0.01 | NDc | ND | <0.001 | — | 200 |
| Cefpirome | 0.5 | 370 | 2 | — | — | — |
| Cefoxitin | 0.2 | 140 | 2 | 50 | 250 | 250 |
| Moxalactam | 2 | 620 | 2 | — | — | 130 |
| Imipenem | 190 | 782 | 250 | 600 | 950 | 700 |
| Meropenem | >190 | >2,000 | 100 | 200 | — | 5,500 |
| Aztreonam | <0.1 | ND | ND | ND | ND | ND |
a
—, not available.
b
In cases of low Km values, Ki values were determined with benzylpenicillin as the substrate.
c
ND, not determinable.
d
Data are means of three independent measurements. Standard deviations were within 15%.