Figure 5.

Dissociation of triple helices in the absence of magnesium in a nondenaturing gel. Samples were prepared in buffer containing 10 mM MgCl₂, loaded onto on a magnesium-free 6% polyacrylamide gel, and then made to migrate at 37°C in TBE buffer in the absence of MgCl₂. Under these triplex denaturing conditions, only the circular padlock comigrates with the plasmid. Plasmid cleavage by XhoI allows the circular padlock to slide away from the linear duplex. In lane 6, the plasmid was added after circularization of the 89-mer, followed by heat denaturation of DNA ligase.