title: Impact of bacterial endotoxin on the structure of DMPC membranes.
abstract: Bacterial lipopolysaccharides are believed to have a toxic effect on human cell membranes. In this study, the influence of a lipopolysaccharide (LPS) from Escherichia coli on the structure, the dynamics and the mechanical strength of phospholipid membranes are monitored by nuclear magnetic resonance spectroscopy (NMR) and by atomic force microscopy (AFM). Model membranes are formed from 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and are either prepared as multilamellar bulk samples or multilamellar vesicles. Field gradient NMR data directly prove the rapid integration of LPS into DMPC membranes. Solid state NMR experiments primarily detect decreasing molecular order parameters with increasing LPS content. This is accompanied by a mechanical softening of the membrane bilayers as is shown by AFM indentation measurements. Altogether, the data prove that lipopolysaccharide molecules quickly insert into phospholipid bilayers, increase membrane fluctuation amplitudes and significantly weaken their mechanical stiffness.
authors.affiliation: Institute of Physical Chemistry, Cenide, University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Nagel
authors.affiliation: Institute of Physiological Chemistry, University of Duisburg-Essen, Hufelandstraße 55, 45122 Essen, Germany; Klinik für Anästhesiologie und Intensivmedizin, University Hospital Essen, University Duisburg-Essen, Hufelandstraße 55, 45122 Essen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Brauckmann
authors.affiliation: Institute of Chemical Technology, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
authors.forename: Franzeska
authors.initials: F
authors.lastname: Moegle-Hofacker
authors.affiliation: Institute of Physiological Chemistry, University of Duisburg-Essen, Hufelandstraße 55, 45122 Essen, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Effenberger-Neidnicht
authors.affiliation: Klinik für Anästhesiologie und Intensivmedizin, University Hospital Essen, University Duisburg-Essen, Hufelandstraße 55, 45122 Essen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hartmann
authors.affiliation: Institute of Physiological Chemistry, University of Duisburg-Essen, Hufelandstraße 55, 45122 Essen, Germany.
authors.forename: Herbert
authors.initials: H
authors.lastname: de Groot
authors.affiliation: Institute of Physical Chemistry, Cenide, University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany. Electronic address: christian.mayer@uni-due.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Mayer
mesh_terms: D019245:Compressive Strength; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D055119:Elastic Modulus; D008051:Lipid Bilayers / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000737:chemistry*; D008560:Membrane Fluidity; D008968:Molecular Conformation; D010539:Permeability; D013314:Stress, Mechanical; D013718:Tensile Strength
chemical_list: D008051:Lipid Bilayers; D008070:Lipopolysaccharides; D004134:Dimyristoylphosphatidylcholine
keywords: Atomic force microscopy; DMPC; Insertion; Lipopolysaccharide; Multilamellar vesicle; Nuclear magnetic resonance spectroscopy