The 2.3 angstrom X-ray structure of nitrite reductase from Achromobacter cycloclastes.
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Godden JW, Turley S, Teller DC, Adman ET, Liu MY, Payne WJ, LeGall J
The 2.3 angstrom X-ray structure of nitrite reductase from Achromobacter cycloclastes.
Science. 1991 Jul 26;253(5018):438-42.
- PubMed ID
- 1862344 [ View in PubMed]
- Abstract
The three-dimensional crystal structure of the copper-containing nitrite reductase (NIR) from Achromobacter cycloclastes has been determined to 2.3 angstrom (A) resolution by isomorphous replacement. The monomer has two Greek key beta-barrel domains similar to that of plastocyanin and contains two copper sites. The enzyme is a trimer both in the crystal and in solution. The two copper atoms in the monomer comprise one type I copper site (Cu-I; two His, one Cys, and one Met ligands) and one putative type II copper site (Cu-II; three His and one solvent ligands). Although ligated by adjacent amino acids Cu-I and Cu-II are approximately 12.5 A apart. Cu-II is bound with nearly perfect tetrahedral geometry by residues not within a single monomer, but from each of two monomers of the trimer. The Cu-II site is at the bottom of a 12 A deep solvent channel and is the site to which the substrate (NO2-) binds, as evidenced by difference density maps of substrate-soaked and native crystals.