Inhibitory activity of l-CA against HIVNL4-3 IN and IN containing the E92K mutation. Purified recombinant IN (A) from HIVNL4-3 or (B) containing an E92K mutation was incubated with the V1-V2 3′-end processing substrate for 1 h at 37°C in triplicate reactions in the presence or absence of l-CA. Lanes: S, substrate without IN; S + IN, substrate with IN; −, in the presence of 25 μM L-tartaric acid, a compound that has no activity against HIV IN; +, in the presence of 25 μM l-CA, a concentration that inhibits catalysis by HIV IN. The numbers above the lanes are the concentrations of l-CA (in μM). For the identifiers on the left, STP, strand transfer products; −2, 3′-end processing products; S, input substrate. The reaction products were separated from the substrate by denaturing PAGE. The percent conversion of substrate to products was quantified by phosphorimager analysis and was used to calculate the IC50s presented in Table 3. (B) Darkening to show the strand transfer products, as this protein is significantly attenuated in the strand transfer reaction (Table 2).