azurin tetramer has a molecular weight of approximately 14kDa, contains a single copper atom, is intensively blue, and has a fluorescence emission band centered at 308 nm.

Azurins and pseudoazurins participate in the denitrification processes in bacteria., including the gram-negative bacteria Pseudomonas aeruginosa, by interacting with cytochrome c551. Azurin from P aeruginosa is a type I blue copper protein