FIG. 5.

MBP-nsp10 5′-to-3′ DNA duplex-unwinding activity. Reaction conditions were as described in Materials and Methods with approximately 25 fmol of DNA substrates per reaction. The structures of the substrates are shown schematically with the radiolabeled strands marked by asterisks. With the exception of DNA-0, which was entirely double-stranded, the substrates consisted of identical 22-bp duplexes to which 30-nt-long, single-stranded oligo(dT) tails were attached at different positions. The reaction products were separated on nondenaturing, 10 to 20% gradient polyacrylamide gels. Lanes: 1, 5, 9, 13, and 17, reactions without protein; 2, 6, 10, 14, and 18, heat-denatured DNA substrates; 3, 7, 11, 15, and 19, reactions containing 2 pmol of MBP-nsp10; 4, 8, 12, 16, and 20, reactions containing 2 pmol of MBP-nsp10-KQ.