Cleavage of wild-type and modified peptide substrates with recombinant PR. Synthetic oligopeptides containing wt (PN, PI, and PC) and modified cleavage sites (P1, P2, P3, P5, and P6) of p6* were cleaved with recombinant HIV-1 PR in a total volume of 200 μl. To monitor cleavage kinetics, 15-μl samples were collected at given time points and analyzed by reverse-phase high-performance liquid chromatography. The data shown are representative of three independent experiments.