TABLE 2.
Kinetic parameters of β-lactamases VIM-2 and VIM-60 with various substrates
| Substrate |
Km (μM)a
|
kcat (s−1)a
|
kcat/Km (μM s−1)a
|
|||
|---|---|---|---|---|---|---|
| VIM-2 | VIM-60 | VIM-2 | VIM-60 | VIM-2 | VIM-60 | |
| Ampicillin | 62 ± 6 | 160 ± 5 | 214 ± 8 | 345 ± 11 | 3.49 | 2.15 |
| Penicillin G | 72 ± 7 | 262 ± 9 | 252 ± 15 | 481 ± 10 | 3.51 | 1.83 |
| Aztreonam | NHb | NH | NH | NH | NH | NH |
| Cefepime | 200 ± 3 | 804 ± 83 | 7.9 ± 0.1 | 85 ± 8 | 0.040 | 0.11 |
| Cefmetazole | 51 ± 2 | 74 ± 7 | 1.9 ± 0.01 | 2.6 ± 0.2 | 0.037 | 0.035 |
| Cefotaxime | 41 ± 5 | 69 ± 1 | 121 ± 4 | 134 ± 2 | 3.00 | 1.93 |
| Cefoxitin | 67 ± 3 | 40 ± 3 | 4.1 ± 0.1 | 2.8 ± 0.02 | 0.061 | 0.069 |
| Cefozopran | 270 ± 8 | 133 ± 10 | 52 ± 1 | 195 ± 7 | 0.19 | 1.47 |
| Cefpirome | 246 ± 5 | 190 ± 2 | 88 ± 1 | 234 ± 2 | 0.36 | 1.23 |
| Ceftazidime | 71 ± 5 | 179 ± 6 | 2.1 ± 0.1 | 7.1 ± 0.2 | 0.030 | 0.040 |
| Ceftriaxone | 87 ± 2 | 54 ± 1 | 58 ± 1 | 33 ± 0.1 | 0.66 | 0.61 |
| Cephradine | 33 ± 0.5 | 94 ± 8 | 102 ± 1 | 68 ± 3 | 3.11 | 0.72 |
| Doripenem | 27 ± 1 | 27 ± 1 | 2.8 ± 0.01 | 2.3 ± 0.03 | 0.10 | 0.084 |
| Imipenem | 81 ± 7 | 40 ± 3 | 46 ± 1 | 13 ± 1 | 0.57 | 0.31 |
| Meropenem | 51 ± 2 | 68 ± 4 | 9.2 ± 0.1 | 16 ± 1 | 0.18 | 0.24 |
| Panipenem | 27 ± 3 | 39 ± 7 | 11 ± 0.2 | 3.6 ± 0.2 | 0.40 | 0.094 |
| Moxalactam | 79 ± 10 | 67 ± 1 | 87 ± 9 | 49 ± 0.2 | 1.10 | 0.73 |
a
Km and kcat were calculated as means ± SD from three independent experiments.
b
NH, no hydrolysis detected with substrate concentrations up to 1 mM and enzyme concentrations up to 700 nM.