Figure 5From: The role of the Zn(II) binding domain in the mechanism of E. coli DNA topoisomerase IReversal of DNA cleavage by topoisomerase I and Top67. A 5'-end labeled 61mer was used as substrate. C: no enzyme added. Lane 1: enzyme cleavage reaction stopped with SDS; Lane 2: enzyme cleavage reaction incubated with 1 M NaCl before SDS treatment; Lane 3: enzyme cleavage reaction incubated with 1 M NaCl and 4 mM MgCl2 before SDS treatment.Back to article page