6IKG:
reference: Carboxypeptidase in prolyl oligopeptidase family: Unique enzyme activation and substrate-screening mechanisms., Yadav P, Goyal VD, Gaur NK, Kumar A, Gokhale SM, Jamdar SN, Makde RD, J Biol Chem. 2019 Jan 4;294(1):89-100. doi: 10.1074/jbc.RA118.004254. Epub 2018, Nov 8. PMID: 30409909

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