1ANE:
reference: Structure of an engineered, metal-actuated switch in trypsin., McGrath ME, Haymore BL, Summers NL, Craik CS, Fletterick RJ, Biochemistry. 1993 Mar 2;32(8):1914-9. PMID: 8448149

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