Figure 3.

The effect of various concentrations of zinc ion on the DNase activity of nuclease-ColE7. A plasmid DNA pUC18 (0.1 µg) was used as the substrate to react with 100 nM nuclease-ColE7. The topological changes of the substrate DNA were monitored by 0.8% agarose gel electrophoresis. The supercoiled (S) form of pUC18 plasmid DNA alone was used as negative control (lane S). The effects of enzymatic reactions with various concentrations of zinc ions were monitored by the conversion of the supercoiled form DNA to its corresponding open circular (O) or linear (L) form. The concentration of zinc ion was increased from 1 nM to 10 mM as indicated on the bottom of each lane.