Figure 1From: Plasmodium serine hydroxymethyltransferase as a potential anti-malarial target: inhibition studies using improved methods for enzyme production and assay Inactivation of PfSHMT (A, B) and PvSHMT (C, D) by thiosemicarbazide. (A and C) show semi-logarithmic plots of residual activities (ln V/V0) versus incubation times at different thiosemicarbazide concentrations. The thiosemicarbazide concentrations used to inactivate PfSHMT (A) were 0.06 mM (●), 0.125 mM (▪), 0.25 mM (△), 0.5 mM (□), and 1 mM (○), while those for PvSHMT (C) were 0.03 mM (●), 0.06 mM (▪), 0.125 mM (△), 0.25 mM (□), and 0.5 mM (○). (B and D) show plots of the observed rate constants (kobs) calculated from the slopes in A and C, respectively, versus thiosemicarbazide concentrations. Based on Equation 1, KI for Pf- and PvSHMT were 0.36 ± 0.07 mM and 0.21 ± 0.08 mM, whereas kinact of Pf- and PvSHMT were 0.0014 ± 0.001 s-1 and 0.0015 ± 0.002 s-1, respectively.Back to article page