Keynote Talk 21st International Conference on Biological Inorganic Chemistry 2025

Coupling nitrogenase to nanocrystals for the light-driven N2 reduction to ammonia. (122219)

Paul W. King 1 , Peter J Dahl 1 , Lauren M Pellows 2 , Zhi-Yong Yang 3 , Bhanu Jagilinki 4 , John W Peters 4 , Lance C Seefeldt 3 , Gordana Dukovic 2 , David W Mulder 1
  1. Biosciences Center, National Renewable Energy Lab, Golden, CO, USA
  2. Department of Chemistry, University of Colorado, Boulder, CO, USA
  3. Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
  4. Stephenson Life Sciences Research Center, The University of Oklahoma, Norman, OK, USA

In the biogeochemical nitrogen cycle, the activation and reduction of dinitrogen (N2) to ammonia (NH3) is accomplished through the catalytic activity of nitrogenases, which are two-component enzyme complexes. The molybdenum (Mo) nitrogenase consists of the iron (Fe) protein and the molybdenum-iron (MoFe) protein. The Fe protein uses the energy from ATP hydrolysis to deliver low potential electrons to the MoFe protein, which catalyzes the reduction of N2 to NH3 at a unique iron-molybdenum metallocofactor, or FeMo-co. We have shown that the function of electron delivery by Fe protein to MoFe protein can be replaced by excited state electron transfer by semiconducting nanocrystals under illumination. We have demonstrated that nanocrystals can bind to MoFe protein to form a biohybrid complex that under illumination catalyzes the reduction of N2 into ammonia. We are using this system to conduct studies of the binding interactions and excited state kinetics to understand how these processes control the efficiencies of electron transfer to MoFe protein. The unique ability to perform light-driven electron delivery to MoFe protein is enabling pre-steady state studies of catalytic intermediates and reaction kinetics. Results of this work are being used to develop kinetic models for understanding the individual parameters controlling the ammonia production rates. Our recent progress on these topics will be presented.

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