The alpha-defensin dimers adsorb onto microbial membrane anionic phospholipids, represented here as a complex of alpha-defensin dimers and a representative set of phospholipid molecules 'membrane anionic phospholipids'. The polar topology of defensins, with their spatially separated charged and hydrophobic regions, allows them to insert into microbial cell membranes, which contains more negatively charged phospholipids than mammalian cell membranes (Lohner et al. 1997). Defensins permeabilize membrane vesicles (Lehrer et al. 1989) with a greater effect on vesicles rich in negatively charged phospholipids (Fuji et al. 1993, Wimley et al. 1994).