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Raman Spectroscopy Of Synthetic Antimicrobial Frog Peptides Magainin 2a And Pgla, Robert W. Williams, Ruth Starman, Kenneth M. P. Taylor, Kenneth Gable, Troy Beeler, Michael Zasloff, David Covell

Uniformed Services University of the Health Sciences

Magainin and PGLa are 23- and 21-residue peptides isolated from the skin of the African clawed frog Xenopus lueuis. They protect the frog from infection and exhibit a broad-spectrum antimicrobial activity in vitro. The mechanism of this activity involves the interaction of magainin with microbial membranes. We have measured the secondary structure and membrane-perturbing ability of these peptides to obtain information about this mechanism. Our results show that mgn2a forms a helix with an average length of less than 20 Å upon binding to liposomes. At high concentrations (50 mg/mL) mgn2a spontaneously solubilizes phosphatidylcholine liposomes at temperatures above the …