Figure 7.

Effects of ebselen on various activities of the NS3 protease/helicase. (A) Schematic for the putative reaction of ebselen with critical cysteine(s) in NS3. (B) Ebselen mainly affects NS3 helicase, not protease, activity. Concentration response of ebselen on RNA binding (squares) as well as ATPase (circles), protease (inverted triangles), and helicase (triangles) activities, reported as normalized activity remaining (n = 2, mean ± SD). (C) Location of cysteines in the HCV NS3 protein. Cys in the helicase domains (d1, d2, and d3) and the protease domain mapped on PDB file 3KQL.⁶ The NS3 chain is colored as a gradient from the N-terminus (blue) to the C-terminus (red). (D) Relative DNA binding affinity (blue), helicase activity (red), and ATPase activity (green) of NS3h_2a(JFH1) (i.e., C431A, C499A) and site-directed mutants C492S/C494S, C279S, and C289S normalized to that of wild-type NS3h_1b(con1). (E) Ability of ebselen to inhibit the various activities of the different NS3h proteins. IC₅₀ values were calculated from 12-point, 2-fold dilutions starting at 100 μM (n = 3, mean ± SD).