Identification of a Novel Carbohydrate-Mimicking Octapeptide from Chemical Peptide Library and Characterization as Selectin Inhibitor

• Published in: Biological & Pharmaceutical Bulletin Vol. 34; no. 6; pp. 883 - 889
• Main Authors: Kawano, Susumu, Iyaguchi, Daisuke, Sasaki, Yusuke, Sekizaki, Haruo, Toyota, Eiko
• Format: Journal Article
• Language: English
• Published: Japan The Pharmaceutical Society of Japan 2011; Pharmaceutical Society of Japan; Japan Science and Technology Agency
• Subjects: Anti-Inflammatory Agents, Non-Steroidal - chemistry; Anti-Inflammatory Agents, Non-Steroidal - metabolism; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Antibodies, Monoclonal - metabolism; Antibody Affinity; carbohydrate mimetic octapeptide; Cross Reactions; Drug Design; E-selectin; E-Selectin - chemistry; E-Selectin - metabolism; Epitopes - metabolism; Humans; Molecular Mimicry; Oligopeptides - chemistry; Oligopeptides - metabolism; Oligopeptides - pharmacology; Oligosaccharides - metabolism; Peptide Library; Selectins - chemistry; Selectins - metabolism; sialyl Lewis X
• ISSN: 0918-6158; 1347-5215
• DOI: 10.1248/bpb.34.883

We found a novel octapeptide (H-YRNWFGRW-NH2) mimicking sialyl Lewis X (sLeX) carbohydrate from a chemical peptide library with anti-sLeX monoclonal antibody (MAb) 2H5. The peptide libraries were constructed by Fmoc-based solid-phase methodology using the mix-split method. The octapeptide sequence was determined by the iterative deconvolution method using anti-sLeX MAb 2H5. To define the important residues for interaction with anti-sLeX MAb 2H5, alanine-scanning analogues of H-YRNWFGRW-NH2 were synthesized. Substitution of Tyr1, Trp4, Arg7 and Trp8 to Ala resulted in a marked drop in affinity. This result indicates that aromatic and cationic amino residues have a key role in interacting with anti-sLeX MAb 2H5. The binding property of the octapeptide was evaluated with anti-sLeX MAb 2H5 and human E-selectin. The octapeptide showed high inhibitory potency (IC50=17.8 nM) for sLeX and competitively inhibited the binding of anti-sLeX MAb 2H5 in a dose-dependent manner. The octapeptide had high affinity (Kd=0.168 μM) for E-selectin and this binding was inhibited by sLeX. These results suggest that octapeptide binds to anti-sLeX MAb 2H5 or E-selectin at the sLeX binding site and sterically interferes with the recognition of anti-sLeX MAb 2H5 or E-selectin with sLeX. This peptide may be a useful lead compound for an anti-inflammatory agent targeting selectin.