ABSTRACT
The amphipathic structure of bacterial endotoxins (lipopolysaccharides, LPS) relates to the supramolecular architecture of lipid A, the biologically active moiety of LPS (1). Lipid A is structurally conserved among LPS from different species of gram-negative bacteria and results from the association of several glycolipid monomers of general structure N,-acyl-ß-1,6-d-glucosamine disaccharide 1,4'-bisphosphate. In an aqueous environment, the glycolipid monomers form micelles according to the critical micellar concentration of the system. Synthetic peptides prepared according to this strategy have been of considerable value in allowing us to elucidate the molecular constraints on amino acid sequences required for efficient thermodynamically stable binding of such peptides to lipid A. Several natural cationic polypeptides of the animal kingdom are known to have antibiotic properties against gram-negative bacteria, at least in part by increasing the permeability of the outer membrane.
