FIGURE 1.

Time-dependent inactivation of caspase-3 by isoquinoline-1,3,4-trione derivatives under air at room temperature. A, progress curves for caspase-3 reaction with Ac-DEVD-pNA in the presence of increasing concentrations of compound III. The assay system containing 2% DMSO was defined for control. The progress curves were fitted by use of a first-order equation to determine the observed inactivation rate (k_obs). B, a replot of k_obs for the progress curves in A as a function of inhibitor concentration. The slope (k_obs/I) of the linear plot was used to quantify the effectiveness of inactivation.