1hcm
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CYTOCHROME CD1 NITRITE REDUCTASE, OXIDISED FROM FROM TETRAGONAL CRYSTALS
OverviewOverview
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 StructureAbout this Structure
1HCM is a Single protein structure of sequence from Paracoccus pantotrophus with SO4, HEC and DHE as ligands. Known structural/functional Sites: , , and . Full crystallographic information is available from OCA.
ReferenceReference
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
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