4UDY:
reference: How the [NiFe S ] Cluster of CO Dehydrogenase Activates CO and NCO, Fesseler J, Jeoung JH, Dobbek H, Angew Chem Int Ed Engl. 2015 Apr 29. doi: 10.1002/anie.201501778. PMID: 25926100

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