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Cluster Models of FeMoco with Sulfide and Carbyne Ligands: Effect of Interstitial Atom in Nitrogenase Active Site

Le, Linh N. V. and Bailey, Gwendolyn A. and Scott, Anna G. and Agapie, Theodor (2021) Cluster Models of FeMoco with Sulfide and Carbyne Ligands: Effect of Interstitial Atom in Nitrogenase Active Site. . (Unpublished)

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Nitrogen-fixing organisms perform dinitrogen reduction to ammonia at an iron-M (M = Mo, Fe, or V) cofactor (FeMco) of nitrogenase. FeMoco displays eight metal centers bridged by sulfides and a carbide having the MoFe₇S₈C cluster composition. The role of the carbide ligand, a unique motif in protein active sites, remains poorly understood. Toward addressing its function, we isolated synthetic models of subsite MFe₃S₃C displaying sulfides and a carbyne ligand. We developed synthetic protocols for structurally related clusters, [Tp*MFe₃₃3X]^(n-), where M = Mo or W, the bridging ligand X = CR, N, NR, S, and Tp* = tris(3,5-dimethyl-1-pyrazolyl)hydroborate, to study the effects of the identity of the heterometal and the bridging X group on structure and electrochemistry. While the nature of M results in minor changes, the μ₃-bridging ligand X has a large impact on reduction potentials, with differences higher than 1 V, even for the same formal charge, the most reducing clusters being supported by the carbyne ligand.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Le, Linh N. V.0000-0003-1451-2675
Bailey, Gwendolyn A.0000-0002-6636-4128
Agapie, Theodor0000-0002-9692-7614
Additional Information:LICENCE: CC BY-NC-ND 4.0 We are grateful to the National Institutes of Health (R01-GM102687B to T.A.), Natural Sciences and Engineering Research Council of Canada (G.A.B.), the Resnick Sustainability Institute at Caltech (G.A.B.), and the National Science Foundation (Graduate Research Fellowships Program to A.G.S.) for funding. We thank the Beckman Institute and the Dow Next Generation Grant for instrumentation support. Michael Takase, Lawrence Henling, and Manar Shoshani are thanked for assistance with crystallography.
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Resnick Sustainability InstituteUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Dow Next Generation Educator FundUNSPECIFIED
Subject Keywords:FeMo cofactor; cubane clusters; nitrogenase; nitrogen fixation; carbide; interstitial ligand; iron-sulfur clusters
Record Number:CaltechAUTHORS:20210524-113358984
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109240
Deposited By: George Porter
Deposited On:24 May 2021 19:46
Last Modified:16 Nov 2021 19:34

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