DETECTION OF LIPOPOLYSACCHARIDE-BINDING PEPTIDES BY THE USE OF A LIPOPOLYSACCHARIDE-COATED PIEZOELECTRIC CRYSTAL BIOSENSOR

A method has been developed to monitor the interaction between a lipop olysaccharide (LPS) and LPS-binding peptides using a piezoelectric qua rtz crystal (PQC). Different pH conditions were evaluated to coat LPS onto AT-cut crystals that had been sputtered with gold and carboxylate d with a 4,4-dithiodi(n-butyric acid). The optimal pH for LPS coating onto the crystal was 4-5. Synthetic peptides that represent different regions of human bactericidal/permeability-increasing protein, BPI (BP I 85-99, BPI 90-101, BPI 157-167) and polymyxin B (PmB) as well as neg ative control peptide (HBsAg 139-147) were utilized to compare their b inding ability to this LPS-coated PQC sensor. The results showed that PmB gave the greatest decrease to the resonant frequency indicating gr eatest binding ability. BPI 85-99, considered the main part of the LPS binding domain of BPI, was the next greatest, while BPI 157-167 and H BsAg 139-147 showed little response. In addition, BPI 90-101 and PmB-m imicking peptide showed intermediate LPS-binding ability, which was le ss than that of BPI 85-99, but was higher than that of BPI 157-167. Th ese results suggest the PQC biosensor is potentially useful for the de tection and comparison of the LPS-binding ability of different peptide s by using an LPS-coated piezoelectric crystal.