Table 1.
Kinetic Constants of SG Mutants
| Relative Activity (%) | Km (μM) | Kcat (s−1) | Kcat/Km (s−1 mM−1) | |
|---|---|---|---|---|
| Wild type | 100 | 90 | 9.8 | 106.4 |
| Phe373Thr | 100 | 2640 | 952.4 | 360.9 |
| Tyr481Phe | 90 | 220 | 27.0 | 121.4 |
| Gly386Ser | 10 | 370 | 3.4 | 9.3 |
| Trp388Ala | 1 | 720 | 0.3 | 0.4 |
| Glu207Asp | <0.1 | ND | ND | ND |
| Glu207Gln | <0.1 | ND | ND | ND |
| Glu416Asp | <0.1 | ND | ND | ND |
| Glu416Gln | <0.1 | ND | ND | ND |
| His161Asn | <0.1 | ND | ND | ND |
| His161Leu | <0.1 | ND | ND | ND |
For relative activity, the activity of the wild-type enzyme is set at 100. The detection limit was 0.1%. For mutants with detectable enzyme activity, further kinetic constants are given. ND, not detectable.