COLL 2 |
| Andrea Hickel, Michael Rappolt, Frank Bringezu, and Karl Lohner. Institute of Biophysics and X-ray Structure Research, Austrian Academy of Sciences, Schmiedlstr. 6, Graz, 8042, Austria |
| Our studies focus on the investigation of the mode of action of antimicrobial peptides. These peptides kill bacteria within minutes by permeation of the cytoplasmic bacterial membrane. Site of action is the lipid matrix and not a specific membrane receptor. For our investigations, we use liposomes as model systems to mimic either bacterial or mammalian cell membranes, which differ markedly in their lipid composition. One of the major phospholipid components in Gram-negative bacterial cell membranes is phosphatidylethanolamine (e.g. 82% of the inner membrane of E.coli). Phosphatidylethanolamines (PEs) have an intrinsic property to curl due to the smaller headgroup area as compared to the cross sectional area required by the acyl chains. Therefore, upon heating they tend to adopt non-lamellar structures, such as inverse hexagonal or cubic phases. We investigated the structural parameters of both the lamellar and inverse hexagonal phase of POPE. For the first time, we could solve the structure of the two co-existing phases at a fixed temperature and derive a model for this phase transition on the molecular level. Furthermore, cubic phase formation could be detected under certain experimental conditions. The knowledge on the promotion of non-lamellar phase formation will help to understand the interaction of antimicrobial peptides with such lipid matrices. |
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ACS Award in Colloid and Surface Chemistry Symposium Honoring Clay Radke
Division of Colloid and Surface Chemistry |