| 2JB4: reference: A Cyclobutanone Analogue Mimics Penicillin in Binding to Isopenicillin N Synthase., Stewart AC, Clifton IJ, Adlington RM, Baldwin JE, Rutledge PJ, Chembiochem. 2007 Sep 28;. PMID: 17907118 |
This OCA 
Structure page
uses Jmol,
developed by the Jmol Development Team
(documentation).