7ADR:
reference: CO binding to the FeV Cofactor of CO-reducing Vanadium Nitrogenase at Atomic Resolution., Rohde M, Grunau K, Einsle O, Angew Chem Int Ed Engl. 2020 Sep 11. doi: 10.1002/anie.202010790. PMID: 32915491

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