4J1L:
reference: Engineering Clostridia Neurotoxins with elevated catalytic activity., Guo J, Pan X, Zhao Y, Chen S, Toxicon. 2013 Nov;74:158-66. doi: 10.1016/j.toxicon.2013.08.055. Epub 2013 Aug, 29. PMID: 23994593

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