Mg2+
optimum activity at 5 mM
Mg2+
requires metal ions for structure and catalysis
Mg2+
the active site contains two metal ions, consistent with the two-magnesium ion catalytic mechanism
Mn2+
activates, showing slightly higher activity than Mg2+
Mn2+
enzyme activity is optimal at 2.5 mM Mn2+
Mn2+
Mg2+ or Mn2+ required
Mn2+
only marginal activity
Mn2+
optimum activity at 1 mM
Mn2+
the enzyme prefers manganese as the metal cofactor for nick sealing