High affinity endotoxin-binding and neutralizing peptides based on the crystal structure of recombinant Limulus anti-lipopolysaccharide factor.
Lipid A, the conserved portion of endotoxin or lipopolysaccharide, is the major mediator of septic shock, and therefore endotoxin-neutralizing molecules could have important clinical applications. The crystal structure of recombinant Limulus anti-lipopolysaccharide factor (rLALF) (Hoess, A., Watson, S., Siber, G. R., and Liddington, R. (1993) EMBO J. 12, 3351-3356), has been used to design synthetic peptides comprising different parts of the exposed amphipathic loop in the proposed endotoxin-binding domain of rLALF. We investigated the minimal requirements of rLALF for endotoxin and lipid A binding with linear 10-mer peptides. Only one linear peptide, corresponding to amino acids 36-45 of rLALF, was able to bind lipid A and endotoxin above background levels. Cyclic peptides, however, bind lipid A and endotoxin with high affinity, presumably by mimicking the three dimensional characteristics of the exposed hairpin loop. The cyclic peptide including amino acids 36-47, LALF-14, has a lipid A binding activity comparable to the high affinity endotoxin-binding peptide polymyxin B. LALF-14 has an improved serum half-life compared with its linear counterpart, and it is not toxic for cultured human monocytes or red blood cells. In mice, it blocks tumor necrosis factor-alpha induction after endotoxin challenge. The characterization of the minimal endotoxin-binding domain of rLALF and, importantly, its structure provided a basis for designing small molecules that could have prophylactic and/or therapeutic properties in humans for the management of septic shock.
Ried
C
C
MorphoSys GmbH, 80807 Munich, Germany.
Wahl
C
C
Miethke
T
T
Wellnhofer
G
G
Landgraf
C
C
Schneider-Mergener
J
J
Hoess
A
A
D000818:Animals; D023181:Antimicrobial Cationic Peptides; D060829:Arthropod Proteins; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D066298:In Vitro Techniques; D007447:Invertebrate Hormones / Q000737:chemistry* / Q000378:metabolism; D008050:Lipid A / Q000378:metabolism*; D051379:Mice; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry; D011112:Polymyxin B / Q000494:pharmacology; D011487:Protein Conformation; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D023181:Antimicrobial Cationic Peptides; D060829:Arthropod Proteins; D007447:Invertebrate Hormones; D008050:Lipid A; D010446:Peptide Fragments; D014409:Tumor Necrosis Factor-alpha; C034705:antilipopolysaccharide factor (Limulus); D011112:Polymyxin B