SearchPublisher and Institutes
You are here: Home :: Area NEM :: Life sciences :: Biochemistry
Klaus Brandenburg, Gudrun Jürgens, Mareike Müller, Satoshi Fukuoka, Michel H.J. Koch
Biophysical Characterization of Lipopolysaccharide and Lipid A Inactivation by Lactoferrin
The interaction of bacterial endotoxins (LPS Re and lipid A, the endotoxic principle of LPS) with the endogenous antibiotic lactoferrin (LF) was investigated using various physical techniques and biological assays. By applying Fouriertransform infrared (FTIR) spectroscopy, we find that LF binds to the phosphate group within the lipid A part and induces a rigidification of the acyl chains of LPS. The secondary structure of the protein as monitored by the amide I band is, however, not changed. Concomitant with the IR data, scanning calorimetric data indicate a sharpening of the acyl chain phase transition. From titration calorimetric and zeta potential data, saturation of LF binding to LPS was found to lie at a : ratio of 1:3 to 1:5 M from the former and 1:10 M from the latter technique. Xray scattering data indicate a change of the lipid A aggregate structure from inverted cubic to multilamellar, and with fluorescence (FRET) spectroscopy, LF is shown to intercalate by itself into phospholipid liposomes and may also block the lipopolysaccharidebinding protein (LBP)induced intercalation of LPS. The LPSinduced cytokine production of human mononuclear cells exhibits a decrease due to LF binding, whereas the coagulation of amebocyte lysate in the Limulus test exhibited concentrationdependent changes. Based on these results, a model for the mechanisms of endotoxin inactivation by LF is proposed.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 382, 08/2001
Pages: 1215 - 1225