FIG. 1.

Site-directed mutagenesis of the HCV NS3 helicase domain. (A) Summary of all mutant clones. The top line sequences represent conserved motifs I, II, III, and VI, respectively, of HCV NS3 helicase. The amino acid residue replacements are shown below the arrows. (B) Purities of mutant proteins. The wild-type and mutant proteins were expressed in E. coli and purified as described in Materials and Methods. Two micrograms of each of the purified proteins was resolved by SDS–12.5% PAGE and stained with Coomassie brilliant blue. WT denotes the wild-type helicase protein.