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Issue 20, 2011
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How does vanadium nitrogenase reduce CO to hydrocarbons?

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Abstract

Nitrogenase enzymes containing molybdenum normally reduce N2 to NH3, and are severely inhibited by CO, but vanadium-nitrogenase reduces CO to hydrocarbons C2H4, C2H6 and C3H8. Aspects of the mechanism of this unexpected and unprecedented reaction have been investigated by density functional simulations of the iron-vanadium cofactor FeV-co [NFe7VS9(homocitrate)] protein-bound by cysteine and histidine. It is found that the intramolecular hydrogenating machinery previously proposed for N2reduction (including H-atom tunneling) can also effect reduction of CO. There are feasible steps for all of the requisite components of the overall reaction, namely (i) the binding of CO, (ii) the initial hydrogenation of CO to HCO, (iii) continued hydrogenations of CO at both C and O to HCOH and H2COH, (iv) eliminations of O as H2O, and (v) the C–C bond formation steps. Intermediate organic fragments can migrate around the active face of FeV-co, and hydrogen bonding between COH functions and S or SH components of FeV-co can occur and contribute to the stabilisation and orientation of intermediates. It is suggested that the difference between Mo-nitrogenase and V-nitrogenase occurs in the immediately surrounding protein, which facilitates (possibly viawater associated with homocitrate bound to V) the exogenous protonation and dehydration of –COH intermediates.

Graphical abstract: How does vanadium nitrogenase reduce CO to hydrocarbons?

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Publication details

The article was received on 12 Feb 2011, accepted on 15 Mar 2011 and first published on 12 Apr 2011


Article type: Paper
DOI: 10.1039/C1DT10240K
Dalton Trans., 2011,40, 5516-5527

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    How does vanadium nitrogenase reduce CO to hydrocarbons?

    I. Dance, Dalton Trans., 2011, 40, 5516
    DOI: 10.1039/C1DT10240K

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