TABLE 3.
Kinetic properties of purified TEM-71 β-lactamase
| Substrate | Mean Vmaxa ± SD | Relative Vmax (%) | Mean Km ± SD (μM) | Relative Vmax/Km (%) |
|---|---|---|---|---|
| Penicillin G | 0.49 ± 0.004 | 100 | 2.1 ± 0.14 | 100 |
| Cephaloridineb | 0.87 ± 0.06 | 180 | 8.3 ± 1.2 | 43 |
| Ceftazidime | 0.11 ± 0.005 | 22 | 100 ± 20 | 0.4 |
| Cefotaxime | 1.1 ± 0.05 | 220 | 73 ± 5.0 | 6.0 |
| Aztreonamc | <0.03 | <6 | NDd | ND |
a
Nanomoles of substrate hydrolyzed per minute per milligram of protein.
b
kcat for cephaloridine was 13 s−1.
c
Values based on estimated Vmax.
d
ND, not determined. The rate of hydrolysis of aztreonam was too low to obtain an accurate Km value.