title: Physico-chemical and biophysical study of the interaction of hexa- and heptaacyl lipid A from Erwinia carotovora with magainin 2-derived antimicrobial peptides.
abstract: The neutralization of endotoxin structures such as the active 'endotoxic principle' lipid A by suitable compounds has been shown to be a key step in the treatment of infectious diseases, in particular in the case of Gram-negative bacteria which frequently may lead to the septic shock syndrome. An effective antimicrobial peptide, originally found in the skin of an African frog, is magainin 2. Here, the interaction of magainin 2-amide and a peptide derived thereof, M2V, with chemically defined and homogeneous hexaacyl and heptaacyl lipids A isolated from LPS of Erwinia carotovora, was investigated. By using Fourier-transform infrared spectroscopy, the gel to liquid crystalline phase transition of the acyl chains of lipid A and the conformation of their phosphate groups due to peptide binding was investigated. The former parameter was also determined by using differential scanning calorimetry. The electrophoretic mobility of lipid A aggregates under the influence of the peptides was studied to determine the Zeta potential, and small-angle X-ray scattering was applied for the elucidation of the types of aggregate structures in the absence and presence of the peptides. The lipid A-induced cytokine production in human mononuclear cells shows that the ability of the two peptides to inhibit a tumor necrosis factor-alpha production correlates with characteristic changes of the biophysical parameters. These are much stronger expressed for the peptide M2V than for magainin 2-amide, which apparently is connected with the higher number of positive as well as more hydrophobic amino acids, leading to a stronger amphiphilicity necessary to neutralize the amphiphilic lipid A aggregates.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, 761-0395, Japan. fukuoka-s@aist.go.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukuoka
authors.forename: Jörg
authors.initials: J
authors.lastname: Howe
authors.forename: Jörg
authors.initials: J
authors.lastname: Andrä
authors.forename: Thomas
authors.initials: T
authors.lastname: Gutsmann
authors.forename: Manfred
authors.initials: M
authors.lastname: Rössle
authors.forename: Klaus
authors.initials: K
authors.lastname: Brandenburg
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008050:Lipid A / Q000737:chemistry*; D054806:Magainins; D016973:Pectobacterium carotovorum / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology; D029867:Xenopus Proteins / Q000737:chemistry* / Q000235:genetics
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008050:Lipid A; D054806:Magainins; D014409:Tumor Necrosis Factor-alpha; D029867:Xenopus Proteins; C053301:magainin 2 peptide, Xenopus