2CEK:
reference: Conformational flexibility in the peripheral site of Torpedo californica acetylcholinesterase revealed by the complex structure with a bifunctional inhibitor., Colletier JP, Sanson B, Nachon F, Gabellieri E, Fattorusso C, Campiani G, Weik M, J Am Chem Soc. 2006 Apr 12;128(14):4526-7. PMID: 16594661

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