Molecular design of LPS-binding peptides

Abstract

Lipopolysaccharide (LPS), a major constituent of the outer membrane of Gram-negative bacteria, is highly toxic and can cause sepsis or septic shock. Therefore, detection of LPS and the ability to neutralize its toxicity is important. We previously obtained a strong LPS-binding peptide, Li5-001, using the phage display method (Matsumoto et al., 2010. J. Microbiol. Methods. 82, 54–58). We modified the sequence the amino acid sequence of this peptide (KNYSSSISSIHAC), by replacing and deleting amino acids to obtain higher LPS-binding affinity and greater resistance to protease digestion. Consequently we obtained a dodecapeptide, Li5-025 (K′YSSSISSIRAC′, K′ and C′ are D-forms of K and C, respectively) which showed a high affinity for LPS, approximately 1000 folds higher affinity than Li5-001 and Kd value of 0.01 nM. By replacing both N- and C-terminal amino acids from L-type to D-type, the peptide was rendered resistant to protease digestion without altering its overall binding capacity.