1XRF:
reference: The crystal structure of a novel, latent dihydroorotase from Aquifex aeolicus at 1.7A resolution., Martin PD, Purcarea C, Zhang P, Vaishnav A, Sadecki S, Guy-Evans HI, Evans DR, Edwards BF, J Mol Biol 2005 May 6;348(3):535-47. PMID: 15826652

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