2FGY:
reference: The Structure of beta-carbonic anhydrase from the carboxysomal shell reveals a distinct subclass with one active site for the price of two., Sawaya MR, Cannon GC, Heinhorst S, Tanaka S, Williams EB, Yeates TO, Kerfeld CA, J Biol Chem. 2006 Mar 17;281(11):7546-55. Epub 2006 Jan 10. PMID: 16407248

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