TABLE 2.
Kinetic parameters for wild-type and high-performance mutant SSAPsa
| Substrate | SSAP variant | kcat (s−1) | Km (mM) | kcat/Km (s−1 · mM−1) |
|---|---|---|---|---|
| Leu-pNA | WT | 41.3 ± 2.6 | 0.57 ± 0.14 | 72.5 |
| D198F F221I | 128 ± 11 | 1.15 ± 0.22 | 111 | |
| Arg-pNA | WT | 1.26 ± 0.2 | 1.00 ± 0.28 | 1.26 |
| D198P F221E | 82.0 ± 5.5 | 7.51 ± 2.3 | 10.9 | |
| Cystinyl-pNA | WT | 3.71 ± 1.2 | 0.11 ± 0.01 | 32.9 |
| D198I F221W | 46.7 ± 8.9 | 0.056 ± 0.01 | 833 |
a
Km and kcat values were calculated from a nonlinear regression fit to the Michaelis-Menten equation, using initial estimates from double-reciprocal plots. The values are means ± standard deviations for three independent experiments. WT, wild type.