5FHQ:
reference: Effects of Active-Site Modification and Quaternary Structure on the Regioselectivity of Catechol-O-Methyltransferase., Law BJ, Bennett MR, Thompson ML, Levy C, Shepherd SA, Leys D, Micklefield J, Angew Chem Int Ed Engl. 2016 Jan 21. doi: 10.1002/anie.201508287. PMID: 26797714

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