FIG. 2.

Effects of atovaquone on P. carinii CoQ biosynthesis. Purified organisms were incubated with [U-¹⁴C]PHBA for 2 days in the presence of different concentrations of the drug. There was a reproducible decrease in PHBA incorporation into CoQ at 10 nM, which then increased to control levels or higher at increased atovaquone concentrations. A decrease to half of the control value (IC₅₀) was then observed with 1 μM atovaquone. Values represent means ± standard errors of the means for four separate experiments.