5KP3:
reference: A Critical Test of the Electrostatic Contribution to Catalysis with Noncanonical Amino Acids in Ketosteroid Isomerase., Wu Y, Boxer SG, J Am Chem Soc. 2016 Sep 1. PMID: 27545569

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