FIG. 5.

Strand-exchange activity of ORF1p. Preannealed duplex DNA ([³²P]29-c29 or [³²P]29-c25) was challenged with a 50× molar excess of the complementary single strand as indicated. Controls contained all components except protein. Lanes 2 and 11, untreated duplex oligonucleotides; lanes 1 and 12, three oligonucleotides in the same proportion as the lanes with protein but heated for 5 min at 95°C and then for 15 min at 45°C. All other samples were incubated for 15 min at 37°C. Recombinant ORF1p from E. coli was added to a final concentration of 17 nM (lanes 3 and 7), 52 nM (lanes 4 and 8), 155 nM (lanes 5 and 9), or 466 nM (lanes 6 and 10). The concentrations of duplex oligonucleotides were 1.6 nM and of single-stranded oligonucleotides were 80 nM.