Nitrite reductase, copper-type (IPR001287)

Short name: NO2-reductase_Cu

Overlapping homologous superfamilies


Family relationships



These enzymes are involved in nitrate assimilation in the denitrification pathway. The 3D structure of the copper-containing nitrite reductase (NIR) from Achromobacter cycloclastes has been determined to 2.3A resolution [PMID: 1862344]. The enzyme is a trimer, each monomer of which contains two Greek key beta-barrel domains (similar to that of plastocyanin) and houses two copper sites. The two copper atoms in the monomer comprise a type I copper site (Cu-I: two His, one Cys and one Met ligand) that plays a crucial role for electron transfer from pseudoazurin to the type II copper site (Cu-II: three His and one solvent ligand), the catalytic centre of NIR for the reduction of nitrite. The Cu-II site lies at the bottom of a 12A deep solvent channel and is the site to which the substrate (NO2-) binds [PMID: 1862344].

GO terms

Biological Process

GO:0006807 nitrogen compound metabolic process
GO:0055114 oxidation-reduction process

Molecular Function

GO:0005507 copper ion binding
GO:0050421 nitrite reductase (NO-forming) activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.