4OU9:
reference: Analysis of carotenoid isomerase activity in a prototypical carotenoid cleavage enzyme, apocarotenoid oxygenase (ACO)., Sui X, Kiser PD, Che T, Carey PR, Golczak M, Shi W, Von Lintig J, Palczewski K, J Biol Chem. 2014 Mar 19. PMID: 24648526

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