Structural Characterization of Two CO Molecules Bound to the Nitrogenase Active Site

As an approach towards unraveling the nitrogenase mechanism, we have studied binding of CO to active-site FeMo-cofactor. is not only inhibitor nitrogenase, but it also a substrate, undergoing reduction hydrocarbons (Fischer–Tropsch-type chemistry). The C?C bond forming capabilities suggest that multiple or CO-derived ligands bind active site. Herein, report crystal structure with two coordinated FeMo-cofactor molybdenum at 1.33 Å resolution. In addition previously observed bridging ligand between Fe2 and Fe6 FeMo-cofactor, new mode revealed through second terminally Fe6. While relevance this state nitrogenase-catalyzed reactions remains be established, highlights privileged roles for in binding, coordination modes available depending on reaction conditions.