Reductant- or Light-Driven ATP-Independent Reduction of CO2 by Nitrogenase MoFe Protein.

Nitrogenase is a versatile metalloenzyme that activates and reduces small molecules like N2, CO, and CO2 into value-added chemicals at ambient conditions. Previously, it is shown that the Mo-nitrogenase could reduce CO2 to CO, but not to hydrocarbons, in an ATP-dependent reaction. Here, it is reported that the ability of the catalytic component of Mo-nitrogenase (MoFe protein) enables ATP-independent reduction of CO2 to up to C4 hydrocarbons in room-temperature reactions driven by a chemical reductant (EuII-DTPA) or visible light (via CdS@ZnS (CZS) quantum dots). Moreover, an opposite deuterium isotope effect is observed on the EuII-DTPA driven reactions of CO2 reduction by MoFe protein and its V-counterpart (VFe protein), in that the former displays higher activities in H2O, and the latter displays higher activities in D2O. These results provide an important foundation for further mechanistic exploration of the nitrogenase-enabled, atypical Fischer-Tropsch type reaction that uses CO2 instead of CO as a substrate; moreover, they serves as a potential template for the future development of nitrogenase-based applications that effectively recycle the greenhouse gas CO2 into valuable fuel products.