Table 3.
Comparative kinetic parameters for SHV-1 and SHV-107 β-lactamases
| Antibiotic | Kinetic parameters of enzyme |
|||||
|---|---|---|---|---|---|---|
| SHV-1b |
SHV-107c |
|||||
| Km (μM)a | kcat (s−1)a | kcat/Km (μM−1 · s−1) | Km (μM)a | kcat (s−1)a | kcat/Km (μM−1 · s−1) | |
| Penicillin G | 23 ± 0.4 | 1,937 ± 82 | 84 | 11 ± 0.9 | 378 ± 6 | 34 |
| Amoxicillin | 31 ± 1 | 1,044 ± 10 | 34 | 42 ± 4 | 657 ± 10 | 16 |
| Ticarcillin | 11 ± 3 | 220 ± 49 | 20 | 23 ± 12 | 51 ± 7 | 2 |
| Piperacillin | 24 ± 0.5 | 1,490 ± 96 | 62 | 31 ± 0.4 | 412 ± 87 | 13 |
| Cephalothin | 40 ± 1 | 128 ± 33 | 3 | 179 ± 9 | <0.1 | <0.001 |
| Ceftazidime | 142 ± 3 | <0.1 | NDd | ND | <0.1 | ND |
| Cefotaxime | 257 ± 21 | <0.1 | ND | ND | <0.1 | ND |
a
Values are means ± standard deviations.
b
The kinetic constants for SHV-1 are from reference 31.
c
E. coli BL21(DE3)(pBK-SHV-107) was the transformant producing SHV-107.
d
ND, not determinable, because the hydrolysis rates were too low.