NosL is one of the accessory proteins of the nos (nitrous oxide reductase) gene cluster. NosL is a monomeric protein of 18,540 MW that specifically and stoichiometrically binds Cu(I). The copper ion in NosL is ligated by a Cys residue, and one Met and one His are thought to serve as the other ligands. It is possible that NosL is a copper chaperone involved in metallo-centre assembly [1].

1: Expression, purification, and characterization of NosL, a novel Cu(I) protein of the nitrous oxide reductase (nos) gene cluster. McGuirl MA, Bollinger JA, Cosper N, Scott RA, Dooley DM; J Biol Inorg Chem 2001;6:189-195. PMID:11293413