Azurocidin (AZU1) is also known as Heparin-binding protein (HBP), Cationic antimicrobial protein CAP37, is a neutrophil granule-derived antibacterial and monocyte- and fibroblast-specific chemotactic glycoprotein. which belongs to the peptidase S1 family and elastase subfamily. AZU1 / HBP contains 1 peptidase S1 domain. AZU1 binds heparin. The cytotoxic action of AZU1 is limited to many species of Gram-negative bacteria; this specificity may be explained by a strong affinity of the very basic N-terminal half for the negatively charged lipopolysaccharides that are unique to the Gram-negative bacterial outer envelope. AZU1 may play a role in mediating recruitment of monocytes in the second wave of inflammation.