1SZR:
reference: Multiple active site conformations revealed by distant site mutation in ornithine decarboxylase., Jackson LK, Baldwin J, Akella R, Goldsmith EJ, Phillips MA, Biochemistry 2004 Oct 19;43(41):12990-9. PMID: 15476392

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