TABLE 5.
Specificity profile by comparison of kinetic parameters for ampicillin and ceftazidime for the wild-type β-lactamase and the β-lactamase with triple mutations
| Substrate | β-Lactamase | kcat (s−1) | Km (μM) | kcat/Km (M−1 s−1) |
|---|---|---|---|---|
| Ampicillin | aTEM-1 | 1,320 ± 150 | 54 ± 9 | (2.5 ± 0.5) × 107 |
| Mutant | 3,220 ± 990 | 440 ± 140 | (7.0 ± 3) × 106 | |
| Ceftazidime | TEM-1 | (1.3 ± 0.4) × 10−2 | 140 ± 45 | (9.0 ± 4.0) × 101 |
| Mutanta | ≤0.05 | ND | (5.90 ± 0.04) × 102 |
a
Determined by integrated Michaelis-Menten equation at [S] << Km.
b
ND, not determined.