1SLU:
reference: X-ray structures of a designed binding site in trypsin show metal-dependent geometry., Brinen LS, Willett WS, Craik CS, Fletterick RJ, Biochemistry 1996 May 14;35(19):5999-6009. PMID: 8634241

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