Table 2. Kinetics for NTP synthesizing activities by PPK1 and PPK2 from M. tuberculosis.
Enzyme | Substrate | Km | kcat | kcat/Km | No. of experiments |
PPK1 | mM | s−1 | mM −1 s −1 | ||
ADP | 0.16±0.024 | 943±12 | 5743±646 | 3 | |
GDP | 11.3±0.6 | 645±3 | 57±3 | 3 | |
PPK2 | |||||
ADP | 8±0.95 | 210±7 | 25.5±2 | 3 |
NTP synthesis assays were carried out following incubation of purified protein (5 µg/reaction for each protein) with 250 µM poly-P20 and different concentrations of ADP (12.5–800 µM for mPPK1 and 1–40 mM for mPPK2) or GDP (1–40 mM). K m and V max values were determined from non-linear regression analysis of Michaelis-Menten equation. For calculating k cat values, molecular masses of the recombinant mPPK1 and mPPK2 are considered as 86 kDa and 36 kDa respectively. Results are presented as Mean ± SD.