title: Lipopolysaccharide interactions of C-terminal peptides from human thrombin.
abstract: Interactions with bacterial lipopolysaccharide (LPS), both in aqueous solution and in lipid membranes, were investigated for a series of amphiphilic peptides derived from the C-terminal region of human thrombin, using ellipsometry, dual polarization interferometry, fluorescence spectroscopy, circular dichroism (CD), dynamic light scattering, and z-potential measurements. The ability of these peptides to block endotoxic effects caused by LPS, monitored through NO production in macrophages, was compared to peptide binding to LPS and its endotoxic component lipid A, and to size, charge, and secondary structure of peptide/LPS complexes. While the antiendotoxic peptide GKY25 (GKYGFYTHVFRLKKWIQKVIDQFGE) displayed significant binding to both LPS and lipid A, so did two control peptides with either selected D-amino acid substitutions or with maintained composition but scrambled sequence, both displaying strongly attenuated antiendotoxic effects. Hence, the extent of LPS or lipid A binding is not the sole discriminant for the antiendotoxic effect of these peptides. In contrast, helix formation in peptide/LPS complexes correlates to the antiendotoxic effect of these peptides and is potentially linked to this functionality. Preferential binding to LPS over lipid membrane was furthermore demonstrated for these peptides and preferential binding to the lipid A moiety within LPS inferred.
authors.affiliation: Department of Pharmacy, Uppsala University, SE-75123, Uppsala, Sweden. shalini.singh@farmaci.uu.se
authors.forename: Shalini
authors.initials: S
authors.lastname: Singh
authors.forename: Martina
authors.initials: M
authors.lastname: Kalle
authors.forename: Praveen
authors.initials: P
authors.lastname: Papareddy
authors.forename: Artur
authors.initials: A
authors.lastname: Schmidtchen
authors.forename: Martin
authors.initials: M
authors.lastname: Malmsten
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D006801:Humans; D008050:Lipid A / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D010455:Peptides / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D055672:Static Electricity; D013917:Thrombin / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D008050:Lipid A; D008070:Lipopolysaccharides; D010455:Peptides; D009569:Nitric Oxide; D013917:Thrombin