Design of a novel membrane-destabilizing peptide selectively acting on acidic liposomes |
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Authors: | Machida S Niimi S Shi X Ando Y Yu Y |
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Institution: | National Food Research Institute, Ministry of Agriculture, Forestry, and Fishery, Tsukuba, Ibaraki, Japan. lili@nfri.affrc.go.jp |
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Abstract: | The design of amphipathic peptides resulted in a novel peptide with a selective ability to destabilize lipid bilayers of acidic liposomes. The newly synthesized peptide, termed mast 21, is a 21-residue long amino acid chain and can only act effectively on acidic liposomes lacking cholesterol. Moreover, mast 21 killed gram-positive and gram-negative bacteria, and it had no hemolytic activity. The antimicrobial and hemolytic activities paralleled the results of membrane destabilizing activity using liposomes. Circular dichroism and Trp-fluorescence emission spectra showed changes in the peptide conformation and circumstances around the peptide during interaction with liposomes. These changes were consistent with an increased alpha-helical content and a less polar environment for the tryptophan residue of the peptide. Mast 21 was observed under dark-field microscopy in real time attacking liposomes. Acidic liposomes were attacked, which resulted in peeling of the lipid bilayer with its subsequent destruction. |
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