2PCD:
reference: Structure of protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa at 2.15 A resolution., Ohlendorf DH, Orville AM, Lipscomb JD, J Mol Biol 1994 Dec 16;244(5):586-608. PMID: 7990141

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