Biological effects of the four potential PhoQ inhibitors.

(a)The Pyrophosphate Reagent detects autophosphorylation. IC50 represents the concentration of the potential PhoQ inhibitor needed to inhibit 50% of SF-PhoQc's autophosphorylation. Values are means ± standard deviations from 3 independent wells. (b)The Luminescent Kinase Assay detects autophosphorylation. IC50 represents the concentration of the potential PhoQ inhibitor needed to inhibit 50% of SF-PhoQc's autophosphorylation. Values are means ± standard deviations from 3 independent wells. (c)KD: Equilibrium Dissociation constant. (d)CC50 represents the concentration of a potential PhoQ inhibitor that results in 50% cytotoxicity of Vero cells. The highest concentration tested is 200 µmol/L. (e)Healthy human erythrocytes were used for the hemolysis assay, and the hemolytic activities of the four potential PhoQ inhibitors are shown at (e)25 µmol/L and (f)100 µmol/L.