1M0I:
reference: Metal ions bound at the active site of the junction-resolving enzyme T7 endonuclease I., Hadden JM, Declais AC, Phillips SE, Lilley DM, EMBO J 2002 Jul 1;21(13):3505-15. PMID: 12093751

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).