TABLE 3.
Kinetic parameters of OXA-232 mutantsa
| Substrate |
Km (μM) |
kcat (s−1) |
kcat/Km (mM−1 · s−1) |
||||||
|---|---|---|---|---|---|---|---|---|---|
| OXA-232-S214E | OXA-232-S214G | OXA-232-S214K | OXA-232-S214E | OXA-232-S214G | OXA-232-S214K | OXA-232-S214E | OXA-232-S214G | OXA-232-S214K | |
| Benzylpenicillin | 140 ± 5 | 95 ± 6.5 | 95 ± 5 | 235 ± 20.6 | 130 ± 11.6 | 115 ± 9 | 1678 ± 91.6 | 1369 ± 166.5 | 1189 ± 72.2 |
| Temocillin | NH | 63 ± 6.7 | 28 ± 3.6 | NH | 0.01 ± 0.007 | 0.03 ± 0.007 | NH | 0.15 ± 0.07 | 1 ± 0.29 |
| Cephalothin | 100 ± 7 | 133 ± 12.1 | 160 ± 13.8 | 8 ± 0.6 | 4 ± 0.6 | 5 ± 0.6 | 81 ± 10.6 | 30 ± 3.8 | 31 ±1.7 |
| Imipenem | >2,000 | 5 ± 2.6 | 6 ± 0.7 | ND | 0.1 ± 0.07 | 0.5 ± 0.014 | ND | 20 ± 6.9 | 83 ± 8.9 |
a
Standard deviation values are indicated after the kinetic parameter values. NH, no detectable hydrolysis was observed with 1 μM purified enzyme or 500 μM substrate; ND, not determined.