1EKJ:
reference: The active site architecture of Pisum sativum beta-carbonic anhydrase is a mirror image of that of alpha-carbonic anhydrases., Kimber MS, Pai EF, EMBO J 2000 Apr 3;19(7):1407-18. PMID: 10747009

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