Structure-Activity Relationship of Model Peptides Based on Pleurocidin, an Antibacterial Peptide

Pleurocidin (Ple) isolated from the skin of the winter flounder is a cationic amphiphilic peptide with antibacterial activity. To search for a simple peptide with strong antibacterial activity but no hemolytic activity, we designed three model peptides based on Ple, Ple I, Ple II, and Ple III. In the model peptides, Leu or Ala, and Lys were used instead of some hydrophobic amino acids and hydrophilic ones in Ple, respectively, to simplify the amino acid composition. The order of their (alpha)-helicity and hydrophobicity is Ple I > Ple II > Ple III. Ple I and Ple II showed antibacterial activity similar to Ple amide (Ple-NH2). However, Ple I had very strong hemolytic activity. Ple III exhibited negligible biological activity. Ple II was found to be a desirable candidate to promote the study of the structure-activity relationship