title: Glycopeptides as oligosaccharide mimics: high affinity sialopeptide ligands for sialoadhesin from combinatorial libraries.
abstract: Two different sialic acid containing glycopeptide (sialopeptide) libraries were synthesized using the portion mixing method and ladder synthesis. The libraries were attached via an IMP spacer and a photolabile linker to PEGA(1900) resin in order to facilitate rapid and unambiguous structural analysis of hits by MALDI-TOFMS. One library contained a lactamized sialic acid moiety at the N terminus of a pentapeptide, while a second library displayed a sialic acid residue at the center of a heptapeptide. The sialopeptide libraries were screened against the recombinant binding domain (SnD1) of a sialic acid binding Ig-like protein, sialoadhesin (Siglec-1). No ligands were identified from the lactamized sialic acid library, underscoring the importance of the carboxylic acid moiety for binding. Screening of the second gave few distinct hits (approximately 0.03% of library) with a high consensus. The high-affinity ligands contained, in most cases, a WG motif following the sialylated Thr. The strength of binding of selected ligands was determined by surface plasmon resonance. The best sialopeptide ligand, WLLT(Sa)WGT, exhibited micromolar affinity of SnD1; >10 times the affinity of SnD1 to 3'-sialyl lactose.
authors.affiliation: Carlsberg Laboratory, Center for Solid-Phase Combinatorial Chemistry, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark.
authors.forename: Koen M
authors.initials: KM
authors.lastname: Halkes
authors.forename: Phaedria M
authors.initials: PM
authors.lastname: St  Hilaire
authors.forename: Paul R
authors.initials: PR
authors.lastname: Crocker
authors.forename: Morten
authors.initials: M
authors.lastname: Meldal
mesh_terms: D001667:Binding, Competitive; D020650:Combinatorial Chemistry Techniques; D004353:Drug Evaluation, Preclinical / Q000379:methods; D006020:Glycopeptides / Q000138:chemical synthesis* / Q000378:metabolism; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism*; D018716:Molecular Mimicry / Q000502:physiology; D009844:Oligosaccharides / Q000502:physiology*; D011971:Receptors, Immunologic / Q000378:metabolism*; D063267:Sialic Acid Binding Ig-like Lectin 1; D012795:Sialoglycoproteins / Q000138:chemical synthesis* / Q000378:metabolism; D020349:Surface Plasmon Resonance
chemical_list: D006020:Glycopeptides; D008024:Ligands; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D011971:Receptors, Immunologic; D063267:Sialic Acid Binding Ig-like Lectin 1; D012795:Sialoglycoproteins