Fig. 5. Effect of divalent cations on recombinant CuquEndo activity. Reaction mixtures containing 1 µl of recombinant CuquEndo and 500 ng of plasmid DNA in a final volume of 20 µl were incubated for 10 min at 37°C in buffers with cation concentration ranging from 0 to 10 mmol l^-1. The digested DNA plasmids were resolved in 1.2% agarose gels and visualized under UV light. (A) MgCl₂. (B) CaCl₂.