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Description
Nitrogenases are enzymes that reduce atmospheric nitrogen (N2) into bioavailable ammonia (NH3), thereby facilitaIng the nitrogen cycle and enabling life on Earth [1,2]. Nitrogenases can be divided into three main classes based on the idenIty of the heteroatom in the acIve site: molybdenum nitrogenase (Mo-nitrogenase), vanadium nitrogenase (V-nitrogenase), and iron- only nitrogenase (Fe-nitrogenase) [3,4]. Mo-nitrogenase, the most acIve and extensively studied among the three classes, has provided valuable insights into nitrogen fixaIon[5]. However, recent aWenIon has shiXed towards V-nitrogenase due to its remarkable ability to bind carbon monoxide (CO) in its resIng state and reduce CO predominantly to ethylene under turnover condiIons [6,7]. The availability of (recent) high-resoluIon (~1Å) X-ray structures of V-nitrogenase provides an excellent starIng point for computaIonal invesIgaIons [8,9]. Here, we employ a hybrid quantum mechanical (QM)/molecular mechanical (MM) approach combined with the Broken Symmetry [10] method to invesIgate the electronic and magneIc properIes that facilitate CO binding to the resIng state of V- nitrogenase. Understanding enzymaIc CO capture and reducIon
informs the design of new enzymes with great biotechnological potenIal.
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[4] Jasniewski, A. J.; Lee, C. C.; Ribbe, M. W.; Hu, Y. Reactivity, Mechanism, and Assembly of the Alternative Nitrogenases. Chem. Rev. 2020, 120 (12), 5107–5157.
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[6] Lee, C. C.; Hu, Y.; Ribbe, M. W. Vanadium Nitrogenase Reduces CO. Science 2010, 329 (5992), 642–642. [7] Hu, Y.; Lee, C. C.; Ribbe, M. W. Extending the Carbon Chain: Hydrocarbon Formation Catalyzed by Vanadium/Molybdenum Nitrogenases. Science 2011, 333 (6043), 753–755.
[8] Rohde, M.; Laun, K.; Zebger, I.; Stripp, S. T.; Einsle, O. Two Ligand-Binding Sites in CO-Reducing V Nitrogenase Reveal a General Mechanistic Principle. Science Advances 2021, 7 (22).
[9] Rohde, M.; Grunau, K.; Einsle, O. CO Binding to the FeV Cofactor of CO-Reducing Vanadium Nitrogenase at Atomic Resolution. Angew. Chem. Int. Ed. 2020, 59 (52), 23626–23630.
[10] Lovell, T.; Li, J.; Liu, T.; Case, D. A.; Noodleman, L. FeMo Cofactor of Nitrogenase: A Density Functional Study of States MN, MOX, MR, and MI. J. Am. Chem. Soc. 2001, 123 (49), 12392–12410.
