Synthesis of fluorescein-labelled O-mannosylated peptides as components for synthetic vaccines: comparison of two synthetic strategies.
Mannose-binding proteins on the surface of antigen-presenting cells (APCs) are capable of recognizing and internalizing foreign agents in the early stages of immune response. These receptors offer a potential target for synthetic vaccines, especially vaccines designed to stimulate T cells. We set out to synthesize a series of fluorescein-labelled O-mannosylated peptides using manual solid phase peptide synthesis (SPPS) on pre-loaded Wang resin, in order to test their ability to bind mannose receptors on human APCs in vitro. A flexible and reliable method for the synthesis of fluorescein-labelled O-mannosylated glycopeptides was desired in order to study their lectin-binding properties using flow cell cytometry. Two synthetic strategies were investigated: incorporation of a fluorescein label into the peptide chain via a lysine side chain epsilon-amino group at the final stage of standard Fmoc solid phase peptide synthesis or attachment of the fluorescein label to the N(alpha)-amino group of a lysine with further incorporation of a mannosylated peptide unit through the side chain N(epsilon)-amino group. The latter strategy proved more effective in that it facilitated SPPS by positioning the growing mannosylated peptide chain further removed from the fluorescein label.
Brimble
Margaret A
MA
Department of Chemistry, University of Auckland, 23 Symonds St, Auckland 1142, New Zealand. m.brimble@auckland.ac.nz
Kowalczyk
Renata
R
Harris
Paul W R
PW
Dunbar
P Rod
PR
Muir
Victoria J
VJ
D000596:Amino Acids / Q000737:chemistry; D000938:Antigen-Presenting Cells / Q000276:immunology; D019793:Fluorescein / Q000737:chemistry*; D006020:Glycopeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D008358:Mannose / Q000737:chemistry*; D013601:T-Lymphocytes / Q000276:immunology; D014614:Vaccines, Synthetic / Q000737:chemistry* / Q000276:immunology*
D000596:Amino Acids; D006020:Glycopeptides; D014614:Vaccines, Synthetic; D008358:Mannose; D019793:Fluorescein