The binding of HCV-796 to NS5B570-Con1 in the nucleoprotein complex of NS5B570-Con1·HCV-cIRES RNA. A, the binding of NS5B570-Con1 to HCV-cIRES RNA. The experiments were carried out with 100 nm NS5B570-Con1, as described under “Experimental Procedures.” The binding curve shows the fractional quenching of NS5B570-Con1 as a result of binding to cIRES-378nt (white diamonds) or cIRES-21nt (white squares). The Kd values are 6.9 ± 0.3 nm for cIRES-378nt and 155.1 ± 16.2 nm for cIRES-21nt (n = 3). B, the binding of HCV-796 to NS5B570-Con1 complexed with HCV-cIRES RNA at the binding equilibrium after 10 min, 40 min, 1 h 10 min, 2 h 10 min, 3 h 10 min, and 4 h 10 min. The NS5B protein was preincubated with RNA for 1 h before adding the compound to initiate the binding equilibrium as described under “Experimental Procedures.” The level of fractional quenching was calculated based on the maximum fluorescence of NS5B-RNA in the absence of the compound.