Antibacterial activities of synthetic peptides corresponding to the carboxy-terminal region of human β-defensins 1–3

The antibacterial activities of synthetic human β-defensin analogs, constrained by a single disulfide bridge and in the reduced form, have been investigated. The peptides span the carboxy-terminal region of human β-defensins (HBD-1–3), which have a majority of cationic residues present in the native defensins. The disulfide constrained peptides exhibited activity against Escherichia coli and Staphylococcus aureus whereas the reduced forms were active only against E. coli. The antibacterial activities were attenuated in the presence of increasing concentrations of NaCl and divalent cations such as Ca2+ and Mg2+. The site of action was the bacterial membrane. Peptides spanning the carboxy-terminal region of human β-defensins could be of help in understanding facets of antimicrobial activity of β-defensins such as salt sensitivity and mechanisms of bacterial membrane damage.