title: Identification of a novel carbohydrate-mimicking octapeptide from chemical peptide library and characterization as selectin inhibitor.
abstract: We found a novel octapeptide (H-YRNWFGRW-NH₂) mimicking sialyl Lewis X (sLe(X)) carbohydrate from a chemical peptide library with anti-sLe(X) 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-sLe(X) MAb 2H5. To define the important residues for interaction with anti-sLe(X) 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-sLe(X) MAb 2H5. The binding property of the octapeptide was evaluated with anti-sLe(X) MAb 2H5 and human E-selectin. The octapeptide showed high inhibitory potency (IC₅₀=17.8 nM) for sLe(X) and competitively inhibited the binding of anti-sLe(X) MAb 2H5 in a dose-dependent manner. The octapeptide had high affinity (K(d)=0.168 µM) for E-selectin and this binding was inhibited by sLe(X). These results suggest that octapeptide binds to anti-sLe(X) MAb 2H5 or E-selectin at the sLe(X) binding site and sterically interferes with the recognition of anti-sLe(X) MAb 2H5 or E-selectin with sLe(X). This peptide may be a useful lead compound for an anti-inflammatory agent targeting selectin.
authors.affiliation: Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Kawano
authors.forename: Daisuke
authors.initials: D
authors.lastname: Iyaguchi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Haruo
authors.initials: H
authors.lastname: Sekizaki
authors.forename: Eiko
authors.initials: E
authors.lastname: Toyota
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000915:Antibody Affinity; D003429:Cross Reactions; D015195:Drug Design; D019040:E-Selectin / Q000737:chemistry / Q000378:metabolism; D000939:Epitopes / Q000378:metabolism; D006801:Humans; D018716:Molecular Mimicry; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D009844:Oligosaccharides / Q000378:metabolism; D019151:Peptide Library; D019087:Selectins / Q000737:chemistry* / Q000378:metabolism; D000080506:Sialyl Lewis X Antigen
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000911:Antibodies, Monoclonal; D019040:E-Selectin; D000939:Epitopes; D009842:Oligopeptides; D009844:Oligosaccharides; D019151:Peptide Library; C546936:SELE protein, human; D019087:Selectins; D000080506:Sialyl Lewis X Antigen; C561575:tyrosyl-arginyl-asparagyl-tryptophyl-phenylalanyl-glycyl-arginyl-tryptophan