Relationship between antimicrobial activity and amphiphilic property of basic model peptides

Abstract

Several cationic model peptides of the prepiece moieties of mitochondrial protein precursors were found to be active against Gram-positive bacteria, but inactive against Gram-negative bacteria. The CD spectra of the model peptides in the presence of phopholipid liposomes demonstrated that antimicrobial activity was generally in parallel with the content of the α-helical amphiphilicity. The results indicate that appropriate positioning of cationic and hydrophobic groups in the stable α-helical structure of the peptides is important to exhibit antimicrobial activity. These peptides also have an ability to leak carboxyfluorescein from acidic and neutral phospholipid vesicles, suggesting that the peptides interact with the bacterial membrane to perturb it.