Figure 3. Efficient DNase activity of rSWAN requires Ca²⁺ and Mg²⁺.

(A) λDNA (0.3 µg) was incubated with recombinant SWAN (rSWAN, 0.1 µg) with or without CaCl₂ (1 mM) and MgCl₂ (1 mM) at 37°C for 1 h. Following electrophoresis, DNA was stained with ethidium bromide and visualized under UV light. The sizes of the λDNA Hind III digest markers are indicated on the left. (B) λDNA (0.3 µg) was incubated with rSWAN (0.1 µg) with varying concentrations of either Ca²⁺ (red circles) or Mg²⁺ (blue circles) at 37°C for 30 min. Using gel images and Image J software, densitometric analyses were performed to calculate % DNA cleavage. Values shown represent the average ± SE of 3 independent experiments.