Permeability of Model Membranes Containing Phospholipids and Lipopolysaccharides: Some Preliminary Results

The outer membrane layer of the cell walls of gram-negative bacteria appears to be highly permeable for small, hydrophilic molecules. The hypothesis that this permeability is due to the presence of lipopolysaccharides was tested by the use of model bilayer membranes consisting of lipopolysaccharides and phospholipids. When closed vesicles bounded by such bilayer structures were tested, it was found that the presence of lipopolysaccharide did not markedly increase their permeability to uncharged organic molecules.