Table 1.
Kinetic properties of Sulfolobus solfataricus amidase and its Y41C mutant (in bold). The turnover number (kcat) was obtained dividing by the molecular mass of the active monomer (55,784 Da); temperature was 70 °C; there were 1–10 µg of enzyme in a total volume of 200 µl incubated for 2–10 min in 50 mM citrate buffer at pH 5.0. Abbreviation: Km = Michaelis constant.
| Substrate | Km (mM) | kcat (sec–1) | kcat/Km (M–1 sec–1) × 102 |
| Acetamide | 22.0 | 28.9 | 13.1 |
| 37.0 | 30.1 | 8.1 | |
| Propionamide | 10.0 | 82.9 | 82.9 |
| 10.0 | 99.4 | 99.4 | |
| Butyramide | 14.0 | 34.3 | 24.5 |
| 3.2 | 17.5 | 54.7 | |
| Isobutyramide | 7.0 | 48.9 | 69.9 |
| 6.5 | 58.4 | 89.8 | |
| Pentanamide | 2.5 | 26.8 | 107.2 |
| 1.5 | 28.6 | 190.6 | |
| Hexanamide | 4.5 | 19.5 | 43.3 |
| 4.5 | 21.6 | 48.0 | |
| Metacrylamide | 0.3 | 4.8 | 160.0 |
| 0.5 | 3.0 | 60.0 | |
| Benzamide | 0.9 | 6.7 | 74.4 |
| 0.6 | 7.2 | 120.0 | |
| p-OH benzamide | 0.1 | 1.9 | 190.0 |
| 0.1 | 2.1 | 210.0 | |
| p-NH2benzamide | 0.2 | 0.8 | 40.0 |
| 0.3 | 2.5 | 83.3 | |
| o-toluamide | 0.1 | 0.4 | 40.0 |
| 0.2 | 0.8 | 40.0 | |
| p-toluamide | 0.2 | 12.2 | 610.0 |
| 0.3 | 14.2 | 473.3 | |
| Nicotinamide | 1.5 | 6.4 | 42.6 |
| 0.4 | 2.2 | 55.0 | |
| 3-phenylpropionamide | 3.0 | 15.3 | 51.0 |
| 2.5 | 18.0 | 72.0 | |
| Indol-3-acetamide | 0.8 | 2.2 | 27.5 |
| 0.8 | 1.2 | 15.0 | |