TABLE 2.
Substrate specificity and kinetic parameters of StoHKa
| Substrate | Km (mM) | Vmax (U mg−1) | kcat/Km (s−1 mM−1) |
|---|---|---|---|
| Glucose | 0.050 ± 0.005 | 67 ± 1.5 | 717 |
| Mannose | 0.13 ± 0.009 | 102 ± 1.9 | 420 |
| Glucosamine | 0.23 ± 0.01 | 106 ± 1.2 | 247 |
| GlcNAc | 0.32 ± 0.006 | 60 ± 0.3 | 100 |
| 2-Deoxyglucose | 0.44 ± 0.01 | 140 ± 1.1 | 170 |
| Fructose | 30 ± 0.7 | 78 ± 0.7 | 1.4 |
| ATP | 0.12 ± 0.007 | 58 ± 1.1 | 259 |
| CTP | 0.52 ± 0.05 | 51 ± 1.5 | 52 |
a
The enzyme activity was measured at 50°C in the presence of 4 mM Mg2+. Substrate specificity for sugars was determined using 2 mM ATP as a phosphoryl donor, and that for phosphoryl donors was determined using 5 mM glucose as a sugar substrate. Kinetic parameters were determined using seven different concentrations of the substrates and by nonlinear regression analysis using KaleidaGraph (Synergy Software).