Figure 4

Cleavage of negatively supercoiled pUC19-NHE plasmid DNA. Reaction was assembled in 50 mM KCl, 10 mM MgCl₂, 50 mM Tris HCl pH 7.5, 0.5 mM DTT, 30 μg/mL BSA with 500 ng of pUC19-NHE plasmid DNA (lane DNA) and 500 ng of proteins topoisomerase I, NmeGp1Sd, human Nme1 and Nme2, as indicated. After 1% SDS, 10 mM EDTA and proteinase K treatment (200 μg/mL) samples were analyzed in 1% agarose gel in TAE buffer and then stained with 0.5 μg/mL ethidium bromide for 30 min. SC marks super coiled DNA, while OC marks open circle/nicked circular DNA.