In this study, the influence of isoleucine and arginine on the biological activity and peptide-membrane interactions
of linear avian β-defensin-4 (RL38) analogs was investigated. Results of biological activities showed that the antimicrobial
activities of AvBD-4 analogs were closely related to hydrophobicity and amphipathicity. The peptide GLI19 with
high hydrophobicity value and amphipathicity displayed broad spectrum antimicrobial activity against both gram-negative
and gram-positive, whereas GLR19 with increasing multiple charges only exhibited activity against gram-negative. The
interaction between peptides and the liposome membrane demonstrated that the peptides preferentially bound to negatively
charged phospholipids over zwitterionic phospholipids, which supported the antimicrobial activity data. The outer
membranes assay further demonstrated that GLI19 had a greater capacity than the other tested peptides to penetrate the
cell membrane at a low concentration. Collectively, the peptides derived from the bactericidal domain of linear β-
defensins by truncation and hydrophobic amino acid substitution may be effective high-potential antibacterial agents.
Keywords: Antimicrobial peptides, biological activity, peptide-membrane interactions, cell selectivity, avian β-defensin-4.
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