This family of enzymes is found in both denitrifying bacteria and fungi which reside in soil and aquatic ecosystems.
Denitrification, the reduction of dissolved nitrate and nitrite to gaseous NO, N20 and N2 is an important process in the recycling of nitrogen in the biosphere, and is a key step in the nitrogen cycle resulting in the loss of terrestrial nitrogen to the atmosphere.
It is chiefly carried out by denitrifying bacteria, which contain nitrate and nitrite reductases. The copper-containing family of enzymes is found in both denitrifying bacteria and fungi which reside in soil and aquatic ecosystems and uses copper ions as cofactors rather than the more common haem cd1
The enzymes in question catalyse the reduction of nitrite (NO2-) to NO + H2O. They contain two copper centres, a Type I centre which receives electrons from pseudoazurin (a copper containing protein), and a type II centre which is the site of nitrite reduction.
Defined by 11 residues: HIS:A-95ASP:A-98HIS:A-100HIS:A-135CYS:A-136HIS:A-145MET:A-150HIS:B-255GLU:B-279THR:B-280HIS:B-306