Table 2. Stereoselectivity of engineered DFPase mutants. 1 U = 1 µmol min−1 .
| Wild type | E37A/Y144A/R146A/T195M | E37D/Y144A/R146A/T195M | |
|---|---|---|---|
| DFP | |||
| Specific activity (U) | 247 ± 10 | 390 ± 21 | 429 ± 21 |
| kcat/Km (M−1 s−1) | 5.6 × 104 | 1.4 × 105 | 9.6 × 104 |
| Sarin (GB) | |||
| Specific activity (U, racemic mixture) | 110 ± 6 | 862 ± 32 | 418 ± 3 |
| (S) kcat/Km (M−1 s−1) | 4.2 × 104 | 2.3 × 105 | 7.1 × 104 |
| (R) kcat/Km (M−1 s−1) | 4.7 × 104 | 4.5 × 104 | 2.4 × 104 |
| Ratio S/R | 0.89 | 5.11 | 2.96 |
| Relative to wild type | 5.74 | 3.33 | |
| Cyclosarin (GF) | |||
| Specific activity (U, racemic mixture) | 198 ± 15 | 258 ± 13 | 143 ± 8 |
| (S) kcat/Km (M−1 s−1) | 1.7 × 104 | 4.9 × 105 | 2.4 × 104 |
| (R) kcat/Km (M−1 s−1) | 7.2 × 105 | 1.3 × 105 | 2.7 × 104 |
| Ratio S/R | 0.02 | 3.77 | 0.89 |
| Relative to wild type | 189 | 44.5 | |