Figure 3.

Activity of the HCV helicase and site-directed mutants at various pH. DNA unwinding assays were performed in MOPS buffers containing either His–Hel (squares), H369A (triangles), H369K (diamonds), E493Q (circles), or E493K (×). All reactions contained 1 nM of duplex [³²P]DNA substrate, 100 nM protein, were initiated with ATP, incubated at 23°C for 10 min, terminated, and analyzed by using native polyacrylamide gels. The average rates obtained from three separate reactions are shown with the standard deviations as error bars.