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Access through your institution Buy or subscribe One leading hypothesis involves dynamic carbon coordination in the Fe–C bonds, which weaken or break to allow the binding of substrates and

intermediates at the Fe atoms. The other proposes a structural role for the carbon atom based on the similarity of the CFe6 motif to that of cementite, the component of carbon steels which

endows toughness. In this collaborative study, carefully targeted 13C isotopic labelling is performed on wild-type and variant (α-Ala70- and α-Ile70-substituted) MoFe protein. Electron

nuclear double resonance (ENDOR) spectroscopy is performed on these enriched species in their ground states as well as after activation with various substrates and inhibitors (N2, propargyl

alcohol (an alkyne) and CO). Notably, the net 13C hyperfine coupling measured is near-zero in all cases, and seemingly invariant to the environment. Density functional theory (DFT)

calculations indicate that the individual contributions of each Fe–C bond to spin transfer are large. Near-zero overall spin of the CFe6 core can therefore only be achieved if there are

three spin-up and three spin-down Fe atoms coordinated to the carbon atom in all these various states. This is inconsistent with hemilabile coordination and a dynamic functional role of the

carbon atom. These findings instead lend support to the idea of an important structural role for this unique carbon atom, holding the FeMo-cofactor together and providing stability as it

undergoes the catalytic cycle. Researchers may need to look elsewhere, such as to the Fe–S bonds, to explain the dynamic coordination behaviour in the nitrogenase active site. This is a

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ACCESS OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Nature Catalysis

https://www.nature.com/natcatal Benjamin Martindale Authors * Benjamin Martindale View author publications You can also search for this author inPubMed Google Scholar CORRESPONDING AUTHOR

Correspondence to Benjamin Martindale. RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Martindale, B. Core strength. _Nat Catal_ 5, 843 (2022).

https://doi.org/10.1038/s41929-022-00866-4 Download citation * Published: 19 October 2022 * Issue Date: October 2022 * DOI: https://doi.org/10.1038/s41929-022-00866-4 SHARE THIS ARTICLE

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