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Mechanism of the Six-Electron Reduction of Nitrite to Ammonia by Cytochrome c Nitrite Reductase

Einsle, Oliver and Messerschmidt, Albrecht and Huber, Robert and Kroneck, Peter M. H. and Neese, Frank (2002) Mechanism of the Six-Electron Reduction of Nitrite to Ammonia by Cytochrome c Nitrite Reductase. Journal of the American Chemical Society, 124 (39). pp. 11737-11745. ISSN 0002-7863. doi:10.1021/ja0206487.

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Cytochrome c nitrite reductase catalyzes the six-electron reduction of nitrite to ammonia without the release of potential reaction intermediates, such as NO or hydroxylamine. On the basis of the crystallographic observation of reaction intermediates and of density functional calculations, we present a working hypothesis for the reaction mechanism of this multiheme enzyme which carries a novel lysine-coordinated heme group (Fe-Lys). It is proposed that nitrite reduction starts with a heterolytic cleavage of the N−O bond which is facilitated by a pronounced back-bonding interaction of nitrite coordinated through nitrogen to the reduced (Fe(II)) but not the oxidized (Fe(III)) active site iron. This step leads to the formation of an {FeNO}^6 species and a water molecule and is further facilitated by a hydrogen bonding network that induces an electronic asymmetry in the nitrite molecule that weakens one N−O bond and strengthens the other. Subsequently, two rapid one-electron reductions lead to an {FeNO}^8 form and, by protonation, to an Fe(II)−HNO adduct. Hereafter, hydroxylamine will be formed by a consecutive two-electron two-proton step which is dehydrated in the final two-electron reduction step to give ammonia and an additional water molecule. A single electron reduction of the active site closes the catalytic cycle.

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Additional Information:© 2002 American Chemical Society. Received May 6, 2002. Publication Date (Web): September 7, 2002. The authors wish to thank Gleb P. Bourenkov and Hans D. Bartunik, MPG-ASMB, DESY Hamburg, for help during synchrotron data collection. This work was supported by Deutsche Forschungsgemeinschaft (F.N., P.K.), German Israeli Foundation (P.K., R.H.), Volkswagenstiftung (P.K.), and Fonds der Chemischen Industrie (F.N.,P.K.). The financial contribution to part of the work by EU ERBF MRX-CT98-0204HU (A.M., R.H.,O.E.) is acknowledged. We wish to dedicate this work to the memory of Achim Kröger.
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
German-Israeli Foundation for Research and DevelopmentUNSPECIFIED
Fonds der Chemischen IndustrieUNSPECIFIED
European UnionMRX-CT98-0204HU
Issue or Number:39
Record Number:CaltechAUTHORS:20170424-153824230
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Official Citation:Mechanism of the Six-Electron Reduction of Nitrite to Ammonia by Cytochrome c Nitrite Reductase Oliver Einsle, Albrecht Messerschmidt, Robert Huber, Peter M. H. Kroneck, and Frank Neese Journal of the American Chemical Society 2002 124 (39), 11737-11745 DOI: 10.1021/ja0206487
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76875
Deposited By: Tony Diaz
Deposited On:24 Apr 2017 22:55
Last Modified:15 Nov 2021 17:03

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