1h9y
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Cytochrome cd(1) nitrite reductase is a bifunctional enzyme, which can | + | Cytochrome cd(1) nitrite reductase is a bifunctional enzyme, which can catalyze the 1-electron reduction of nitrite to nitric oxide and the 4-electron reduction of dioxygen to water. Here we describe the structure of reduced nitrite reductase, crystallized under anaerobic conditions. The structure reveals substantial domain rearrangements with the c domain rotated by 60 degrees and shifted by approximately 20 A compared with previously known structures from crystals grown under oxidizing conditions. This alternative conformation gives rise to different electron transfer routes between the c and d(1) domains and points to the involvement of elements of very large structural changes in the function in this enzyme. In the present structure, the c heme has a His-69/Met-106 ligation, and this ligation does not change upon oxidation in the crystal. The d(1) heme is penta-coordinated, and the d(1) iron is displaced from the heme plane by 0.5 A toward the proximal ligand, His-200. After oxidation, the iron moves into the d(1) heme plane. A surprising finding is that although reduced nitrite reductase can be readily oxidized by dioxygen in the new crystal, it cannot turnover with its other substrate, nitrite. The results suggest that the rearrangement of the domains affects catalysis and substrate selectivity. |
==About this Structure== | ==About this Structure== | ||
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[[Category: oxidoreductase]] | [[Category: oxidoreductase]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:59:07 2008'' |
Revision as of 10:59, 21 February 2008
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CYTOCHROME CD1 NITRITE REDUCTASE, REDUCED FORM COMPLEXED TO CN
Overview
Cytochrome cd(1) nitrite reductase is a bifunctional enzyme, which can catalyze the 1-electron reduction of nitrite to nitric oxide and the 4-electron reduction of dioxygen to water. Here we describe the structure of reduced nitrite reductase, crystallized under anaerobic conditions. The structure reveals substantial domain rearrangements with the c domain rotated by 60 degrees and shifted by approximately 20 A compared with previously known structures from crystals grown under oxidizing conditions. This alternative conformation gives rise to different electron transfer routes between the c and d(1) domains and points to the involvement of elements of very large structural changes in the function in this enzyme. In the present structure, the c heme has a His-69/Met-106 ligation, and this ligation does not change upon oxidation in the crystal. The d(1) heme is penta-coordinated, and the d(1) iron is displaced from the heme plane by 0.5 A toward the proximal ligand, His-200. After oxidation, the iron moves into the d(1) heme plane. A surprising finding is that although reduced nitrite reductase can be readily oxidized by dioxygen in the new crystal, it cannot turnover with its other substrate, nitrite. The results suggest that the rearrangement of the domains affects catalysis and substrate selectivity.
About this Structure
1H9Y is a Single protein structure of sequence from Paracoccus pantotrophus with , , and as ligands. Known structural/functional Sites: , , and . Full crystallographic information is available from OCA.
Reference
The Structure of an alternative form of Paracoccus pantotrophus cytochrome cd(1) nitrite reductase., Sjogren T, Hajdu J, J Biol Chem. 2001 Aug 3;276(31):29450-5. Epub 2001 May 23. PMID:11373294
Page seeded by OCA on Thu Feb 21 12:59:07 2008
Categories: Paracoccus pantotrophus | Single protein | Hajdu, J. | Sjogren, T. | CYN | DHE | HEC | SO4 | Cn | Enzyme | Nitrite reductase | Oxidoreductase
