3BOC:
reference: Structure and metal exchange in the cadmium carbonic anhydrase of marine diatoms., Xu Y, Feng L, Jeffrey PD, Shi Y, Morel FM, Nature. 2008 Mar 6;452(7183):56-61. PMID: 18322527

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