2W2D:
reference: Crystal structure of a catalytically active, non-toxic endopeptidase derivative of Clostridium botulinum toxin A., Masuyer G, Thiyagarajan N, James PL, Marks PM, Chaddock JA, Acharya KR, Biochem Biophys Res Commun. 2009 Mar 27;381(1):50-3. Epub 2009 Feb 8. PMID: 19351593

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