Fig. 4
(A) Potential activating/inhibiting compounds added to the assays in addition to ammonium* (NH4+) which appears to be required by PfkA to produce substantial activity. The velocity of the enzyme in each reaction was recorded in the presence of 2Â mM substrate, 2Â mM phosphate donor and 2Â mM effector. G6P-glucose-6-phosphate, PEP-phosphoenolpyruvate. (B) Relative activity of the enzyme with potential activating/ inhibiting compounds added to the assays in addition to ammonium* (NH4+) compared to assays with only NH4Cl added with ATP as the phosphate donor while (C) utilized GTP. (D) Relative activity of recombinant PfkA in the presence of various concentrations of PPi for both phosphate donors. The concentration of Mg2+ in the assay was reduced 50% to 2.5Â mM to avoid precipitation with PPi.. All assays were performed in triplicate