Table 2.
TMPK | Km (ATP) (mM) | Km (dTMP) (μM) | Vm (ATP, dTMP) (μmole/min • mg of protein) | kcat (s−1) |
M. tuberculosis | 0.1 | 4.5 | 13 | 4.5 |
E. coli | 0.04 | 15 | 50 | 10.5 |
Yeasta | 0.19 | 9 | 84 | 35 |
a Results from yeast were from Lavie et al. 1998a.
The reaction medium (0.5 mL final volume) contained 50 mM Tris-HCl pH 7.4, 50 mM KCl, 2 mM MgCl2, 0.2 mM NADH, 1 mM phosphoenol pyruvate, and 2 units each of lactate dehydrogenase, pyruvate kinase and nucleoside diphosphate kinase. Activity was determined at 30°C as described under Materials and Methods. ATP was constant (0.2, 0.3, 0.4, and 0.7 mM) whereas the concentration of dTMP varied between 0.025 and 0.2 mM.