2Q2N:
reference: Porphyrin binding and distortion and substrate specificity in the ferrochelatase reaction: the role of active site residues., Karlberg T, Hansson MD, Yengo RK, Johansson R, Thorvaldsen HO, Ferreira GC, Hansson M, Al-Karadaghi S, J Mol Biol. 2008 May 16;378(5):1074-83. Epub 2008 Mar 28. PMID: 18423489

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