Fig. 11. Summary of Contributions of Metal Ion Equivalents to DNA Binding by PvuII Endonuclease.

For EM₂, energy represents the difference between DNA binding in the absence of metal ions (K_d 300 nM) and in the presence of one metal ion equivalent per active site; for EM₄, the increased binding energy relative to EM₂ is represented. Energies were calculated using the equations ΔG = −RT ln(K_{d E}/K_{d EM2}) and ΔG = −RT ln(K_{d EM2}/K_{d EM4}).