Tests of the metal cofactor effects of HIV-1 IN inhibitors on HIV-1 and ASV IN joining activities. A. Dose response curves showing the joining activities of HIV-1 and ASV IN (at 1 μM concentration) as a function of increasing concentration of compound 1. Triplicate data are plotted for each inhibitor concentration and the curves show non-linear regression fitting of the data using Visual Enzymics software. The solid and open triangles represent HIV-1 IN activity in the presence of Mn++ or Mg++ cofactors, respectively. The solid and open squares represent ASV IN activity in the presence of Mn++ or Mg++ cofactors, respectively. B. Comparison of the IC50 values obtained by gel and solution based methods. The structure of the inhibitors is shown to the left of the table. Previously published values for IC50s with HIV-1 IN are shown on the left, while values on the right for both HIV-1 and ASV IN were obtained with the solution assay described here. The latter values were determined from non-linear fitting of the triplicate data to a four parameter sigmoidal dose response equation, with the standard error of the fit shown for compounds 1 and 3. Data for compound 2 are from a single experiment.