Comparison of the membrane interaction and permeabilization by the designed peptide Ac-MB21-NH2 and truncated dermaseptin S3

Ac-MB21-NH2 (Ac-FASLLGKALKALAKQ-NH2) and dermaseptin S3(1-16)-NH2 (AL-WKNMLKGIGKLAGK-NH2) are cationic amphipathic peptides with antimicrobial activity against a broad spectrum of microorganisms including various fungi. The interaction of the peptides with liposomes was studied by exploiting the tryptophan fluorescence of F1W-Ac-MB21-NH2 and dermaseptin S3(1-16)NH2. Spectral analysis and the use of quenchers indicate that the tryptophans of both peptides insert more deeply in anionic than in zwitterionic liposomes. Membrane insertion con-elates with the formation of an alpha-helical peptide structure. Both peptides permeabilize liposomes composed of anionic, cylindric phospholipids more efficiently than liposomes formed of zwitterionic, conic (phospho)lipids.