2E81

Cytochrome c Nitrite Reductase from Wolinella succinogenes with bound intermediate hydroxylamine

Summary for 2E81

• Entry DOI: 10.2210/pdb2e81/pdb
• Related: 1FS7 1FS8 1FS9 2E80
• Descriptor: Cytochrome c-552, CALCIUM ION, YTTRIUM (III) ION, ... (6 entities in total)
• Functional Keywords: multiheme cytochrome, nitrite reductase, reaction intermediate, oxidoreductase
• Biological source: Wolinella succinogenes
• Cellular location: Periplasm : Q9S1E5
• Total number of polymer chains: 1
• Total formula weight: 58765.86

Authors

Einsle, O.,Kroneck, P.M.H. (deposition date: 2007-01-15, release date: 2007-01-30, Last modification date: 2024-11-06)

Primary citation

Einsle, O.,Messerschmidt, A.,Huber, R.,Kroneck, P.M.H.,Neese, F.
Mechanism of the six-electron reduction of nitrite to ammonia by cytochrome c nitrite reductase
J.Am.Chem.Soc., 124:11737-11745, 2002

PubMed Abstract: 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.

PubMed: 12296741
DOI: 10.1021/ja0206487

Experimental method

X-RAY DIFFRACTION (2 Å)