4BB3:
reference: The crystal structure of isopenicillin N synthase with a dipeptide substrate analogue., Daruzzaman A, Clifton IJ, Adlington RM, Baldwin JE, Rutledge PJ, Arch Biochem Biophys. 2013 Feb 1;530(1):48-53. doi: 10.1016/j.abb.2012.12.012., Epub 2012 Dec 19. PMID: 23262315

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