Application of Thiol-yne/Thiol-ene Reactions for Peptide and Protein Macrocyclizations

Chemistry. 2017 May 23;23(29):7087-7092. doi: 10.1002/chem.201700572. Epub 2017 Apr 26.


The application of thiol-yne/thiol-ene reactions to synthesize mono- and bicyclic-stapled peptides and proteins is reported. First, a thiol-ene-based peptide-stapling method in aqueous conditions was developed. This method enabled the efficient stapling of recombinantly expressed coil-coiled proteins. The resulting stapled protein demonstrated higher stability in its secondary structure than the unstapled version. Furthermore, a thiol-yne coupling was performed by using an α,ω-diyne to react with two cysteine residues to synthesize a stapled peptide with two vinyl sulfide groups. The stapled peptide could further react with another biscysteine peptide to yield a bicyclic stapled peptide with enhanced properties. For example, the cell permeability of a stapled peptide was further increased by appending an oligoarginine cell-penetrating peptide. The robustness and versatility of thiol-yne/thiol-ene reactions that can be applied to both synthetic and expressed peptides and proteins were demonstrated.

Keywords: peptide macrocyclization; peptide stapling; thiol-ene coupling; thiol-yne coupling.

MeSH terms

  • Amino Acid Sequence
  • Cell-Penetrating Peptides / chemistry*
  • Chromatography, Gel
  • Cyclization
  • Cysteine / chemistry
  • Protein Structure, Secondary
  • Sulfhydryl Compounds / chemistry*
  • Sulfides / chemistry*


  • Cell-Penetrating Peptides
  • Sulfhydryl Compounds
  • Sulfides
  • Cysteine