Crystallization of antimicrobial pores in membranes: Magainin and protegrin

Membrane pores spontaneously formed by antimicrobial peptides in membranes were crystallized for the first time by manipulating the sample hydration a nd temperature. Neutron diffraction shows that magainins and protegrins for m stable pores in fully hydrated fluid membranes. At lower hydration levels or low temperature, the membrane multilayers crystallize. In one crystalli ne phase, the pores in each bilayer arrange in a regular hexagonal array an d the bilayers are stacked into a hexagonal ABC lattice, corresponding to t he cubic close-packed structure of spheres. In another crystalline phase, t he bilayers are modulated into the rippled multilamellae, corresponding to a 2D monoclinic lattice. The phase diagrams are described. Crystallization of the membrane pores provides possibilities for diffraction studies that m ight provide useful information on the pore structures.