FIG. 5.

The fast-migrating topoisomer generated by ligation of IS95 in the presence of HMG2 is unwound by one helical turn with respect to the relaxed 263-bp circle with an Lk of 25. Lane 1, linear monomer 263-bp IS95; lanes 2 to 5, purified band b (Lk24) untreated or treated with wheat germ topoisomerase I (TI wg), calf thymus topoisomerase I (TI thy), E. coli topoisomerase I (TI E. coli), or DNase I (D), as indicated above the lanes; lanes 7 to 11, purified band a (Lk25) untreated or treated as for Lk24, as indicated above the lanes. Sizes of molecular mass markers are indicated in base pairs on the left.