FIG. 5.
Helicase activity of purified native and dephosphorylated wild-type NS1 (A) and NS1dlC67 (B). Helicase assays were carried out by incubating 20 ng of M13-VAR (32P-labeled fragments of various lengths annealed to circular M13 DNA) with the indicated amounts (in nanograms) of NS1 in the presence of ATP. The reaction products were analyzed by nondenaturing 7% PAGE in the presence of 0.1% SDS. NS1 mutant K405R served as a negative control. Native (NAT) and heat-denatured (DEN) input DNA are shown on the left as references.