Spontaneous polymerization of the antibiotic peptide magainin 2.

We describe here the ability of the magainin 2 peptide to assemble spontaneously into characteristic 13-nm diameter filaments having a 30 nm periodic helical substructure. Optimal conditions for extensive polymerization into filaments of several hundred microns required low pH and high ionic strength. Polymerization of the magainin 2 peptide may be involved in its recently described in vitro membrane-disrupting and antibiotic activities.