1E8K:
reference: The First Direct Determination of a Ligand Binding Constant in Protein Crystals., Wu Sy S, Dornan J, Kontopidis G, Taylor P, Walkinshaw MD, Angew Chem Int Ed Engl. 2001 Feb 2;40(3):582-586. PMID: 11180378

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