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. 2011 Nov 14;6(11):e27398. doi: 10.1371/journal.pone.0027398

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.