Cathelicidin antimicrobial peptide is the only cathelicidin protein found in humans and is location on chromosome 3p21. The sequence contains 4 exons and is translated to hCAP18, a pre-pro-protein, containing signal peptide, a conserved pro-sequence (cathelin-like domain) and a C-terminal antimicrobial peptide, LL-37. The active LL-37 peptide is produced from proteolytic cleavage from hCAP18 and its primary structure is based on 37 amino acid residues (~ 18kDa), which form an amiphiphatic alpha-helix (secondary) structure.


The LL-37 peptide functions in host response to infection. The peptide inhibits bacterial biofilm production and has antimicrobial (antibacterial, antiviral and fungicidal) functions. The LL-37 peptide has been demonstrated to bind to bacterial lipopolysaccharides, have pore forming capabilities, regulate inflammation via membrane-mediated receptors and act as a chemoattractant of immune cells. In addition to the antimicrobial effects, peptide inhibits tumour growth, induces mastocyte chemotaxis, functions in cellular apoptosis and positively affects the wound healing process by stimulating angiogenesis and epithelial recovery.