FIG. 3.

Identification of the inhibition site of the respiratory chain of Leishmania by TFQ. (A and B) Inhibition of the oxygen consumption rates of permeabilized L. donovani promastigotes in the presence of 5 mM succinate as the substrate. The arrows indicate the addition of the indicated substrates and inhibitors at their respective final concentrations as stated: 60 μM digitonin, 100 μM ADP, 0.1 mM TMPD plus 1.7 mM ascorbate, 2 mM malonate, 6.7 mM α-glycerophosphate (α-GP), and 5 μM TFQ. (C) Inhibition of CcR activity by TFQ. CcR activity ± SD was monitored by the increase of absorbance at 550 nm due to the reduction of initially oxidized cytochrome c solution (32 μM) after addition of different TFQ concentrations to mitochondrial fraction as described in Materials and Methods. Samples without succinate or in the presence of antimycin A, as the inhibitor of CcR, were considered as controls. Activity was measured at 37°C.