ISOLATION OF ANTIMICROBIAL PEPTIDES FROM AVIAN HETEROPHILS

Five bactericidal peptides (chicken heterophil peptides CHP1 and CHP2; turkey heterophil peptides THP1, THP2, and THP3) were purified from a vian heterophil granules. All peptides were cationic and rich in cyste ine, arginine, and lysine. The complete amino acid sequence, consistin g of 39 amino acids, was determined for CHP1. This peptide had a molec ular weight of 4481 as determined by mass spectrometry. Partial NH2-te rminal amino acid sequences were obtained for the remaining peptides. Both chicken peptides and THP1 shared sequence homology at 22 residues and a cysteine motif which was similar to that of bovine beta-defensi ns. THP2 and THP3 were homologous to each other but were not homologou s to the other three and had a unique cysteine motif. Peptides CHP1, C HP2, and THP1 killed Staphylococcus aureus and Escherichia coli in vit ro, whereas THP2 and THP3 killed only S. aureus in vitro.