Figure 3. DNA cleavage activity of the catalytic residue mutants.

Purified protein of WT, H294D, H295A and H320A were assayed as described in Materials and Methods in the presence of 2 mM NiSO₄. Five μl of undiluted, three-fold and nine-fold dilutions of 1.5 mg/ml of enzyme solution were assayed on 1 µg of λ DNA.