RNA unwinding by NS3-4A variants. The unwinding parameters of the 34-bp RNA duplex RNA2 for NS3 (solid diamonds) are A = 0.67 ± 0.02 and kobs = 0.020 ± 0.002 s−1; for NS3-4A (solid circles), they are A = 0.41 ± 0.02 and kobs = 0.020 ± 0.002 s−1; for NS3-4A Y1702A (solid squares), they are A = 0.13 ± 0.01 and kobs = 0.06 ± 0.01 s−1; for NS3-4A M1708A (crossed circles), they are A = 0.13 ± 0.01 and kobs = 0.06 ± 0.01 s−1; for NS3-4A S1369R (hatched squares), they are A = 0.74 ± 0.02 and kobs = 0.03 ± 0.01 s−1; for NS3-4A S1369R/M1708A (hatched diamonds), they are A = 0.70 ± 0.02 and kobs = 0.02 ± 0.01 s−1; and for NS3-4A S1369R/Y1702A (hatched circles), they are A = 0.35 ± 0.01 and kobs = 0.04 ± 0.01 s−1. These data are the averages of three experiments, and the error represents the standard deviation.