1SX5:
reference: DNA Cleavage by EcoRV Endonuclease: Two Metal Ions in Three Metal Ion Binding Sites., Horton NC, Perona JJ, Biochemistry 2004 Jun 8;43(22):6841-57. PMID: 15170321

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