FIG. 1.

Kinetics of alternative complex I (PfNDH2) activity in P. falciparum. (A) Concentration dependence of rotenone-insensitive oxidation of NADH in cell-free parasite extracts with CoQ₁ as an exogenous substrate. Data points are means of results from three individual experiments. (B) Concentration-dependent DPI inhibition of PfNDH2 enzyme activity with CoQ₁ as an exogenous substrate. Data points are means from duplicate observations from three individual experiments. Data were fitted to a function describing simple ligand binding at a single site by nonlinear regression analysis (Marquart method) using an iterative procedure to generate the best fit (χ²) of the curve to the data. Standard errors were calculated for each parameter using the matrix inversion method (Grafit user manual).