1Q4G:
reference: The 2.0 A resolution crystal structure of prostaglandin H2 synthase-1: structural insights into an unusual peroxidase., Gupta K, Selinsky BS, Kaub CJ, Katz AK, Loll PJ, J Mol Biol 2004 Jan 9;335(2):503-18. PMID: 14672659

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