Synthesis and evaluation of fluorescent Pam3Cys peptide conjugates

Geoffroy P.P. Gential, Nataschja I. Ho, Fabrizio Chiodo, Nico Meeuwenoord, Ferry Ossendorp, Herman S. Overkleeft, Gijs A. van der Marel, Dmitri V. Filippov

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Chirally pure R- and S-epimers of TLR2 ligand Pam3CysSK4were prepared and separately conjugated to an OVA model epitope, in which lysine was replaced by azidonorleucine. The azide function in the conjugate permitted labelling with different fluorophores by use of strain-promoted 3+2 cycloaddition. The R-epimer of the labelled conjugates induced TLR2-dependent DC maturation, while S-epimer proved to be inactive. Combining the lipophilicity of Pam3CysSK4ligand with fluorophores influenced the solubility of the resulting conjugates in an unpredictable way and only the conjugates labelled with Cy-5 were suitable for confocal fluorescence microscopy experiments. It was shown that both epimers of the Cy-5 labelled lipopeptides were internalized equally well, indicating TLR2-independent cellular uptake. The presented results demonstrate the usefulness of strain-promoted azide-alkyne cycloaddition in the labelling of highly lipophilic lipopeptides without disturbing the in vitro activity of these conjugates with respect to activation of TLR-2.

Original languageEnglish
Pages (from-to)3641-3645
Number of pages5
JournalBioorganic and Medicinal Chemistry Letters
Issue number15
Publication statusPublished - 1 Jan 2016
Externally publishedYes


  • Fluorescent labeling
  • Lipopeptides
  • Strain promoted cycloaddition
  • Toll-like receptor 2

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