4ZUN:
reference: Design, Synthesis, and Evaluation of Polyamine Deacetylase Inhibitors, and High-Resolution Crystal Structures of Their Complexes with Acetylpolyamine Amidohydrolase., Decroos C, Christianson DW, Biochemistry. 2015 Aug 4;54(30):4692-703. doi: 10.1021/acs.biochem.5b00536. Epub , 2015 Jul 22. PMID: 26200446

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