TABLE 7.
Kinetic parameters of wild-type and mutant β-lactamases for cefazolin
| β-Lactamase | kcat (s−1) | Km (μM) | kcat/Km (μM−1 · s−1) | Relative valuea |
|---|---|---|---|---|
| S289b | 3,790 ± 220 | 1,150 ± 50 | 3.3 ± 0.2 | 1.00 |
| S289A | 3,050 ± 90 | 1,020 ± 40 | 3.0 ± 0.1 | 0.91 |
| S289T | 2,380 ± 150 | 850 ± 40 | 2.8 ± 0.2 | 0.85 |
| S289Q | 4,730 ± 230 | 1,760 ± 70 | 2.7 ± 0.1 | 0.82 |
| S289R | 2,880 ± 200 | 1,770 ± 70 | 1.6 ± 0.1 | 0.49 |
| S289K | 3,840 ± 250 | 2,260 ± 90 | 1.7 ± 0.1 | 0.52 |
| S289C | 2,620 ± 150 | 1,890 ± 110 | 1.4 ± 0.1 | 0.42 |
a
Ratio of kcat/Km of the mutant β-lactamase to that of the wild-type enzyme.
b
Wild type.