Poster Presentation 8th Modern Solid Phase Peptide Synthesis & Its Applications Symposium 2022

Late-stage modification of peptides and proteins at cysteine with diaryliodonium salts (#104)

Stephen A Byrne 1 2 , Max J Bedding 1 2 , Leo Corcilius 1 2 , Daniel J Ford 1 2 , Yichen Zhong 3 , Charlotte Franck 1 2 3 , Mark Larance 3 4 , Joel P Mackay 2 3 , Richard J Payne 1 2
  1. School of Chemistry, The University of Sydney, Sydney, NSW, Australia
  2. Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW, Australia
  3. School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
  4. Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia

Peptides and proteins bearing defined modifications, including posttranslational modifications (PTMs), fluorophores or bioactive entities are of enormous value for basic science and for the burgeoning biotechnology sector.1 This has led to significant interest in the development of novel methods for the late-stage functionalisation of these biomolecules. Late-stage modification of cysteine (Cys) residues within peptides and proteins is a highly attractive strategy due to the unique nucleophilicity and redox properties of this amino acid, imparting higher degrees of chemoselectivity during modification. Additionally, its low abundance within the proteome can result in greater regioselectivity and site-specificity. Despite the development of several methods to modify peptides and proteins at Cys,2 these strategies suffer from a number of significant drawbacks including poor chemoselectivity and conversion, low conjugate stability (i.e. retro-Michael addition of maleimides), and insufficient biocompatibility (high temperatures, organic solvents, excessive reagents equivalents). 

We have demonstrated that diaryliodonium reagents can be used for the chemoselective and mild arylation of Cys residues to access stable thioether-linked peptide and protein conjugates.3 Functionalisation of peptides and recombinant proteins proceeds rapidly (1-3 h) with high conversions and under mild and biocompatible conditions (aqueous buffer, 37 ˚C, pH 8). The power of this novel bioconjugation platform is demonstrated by the late-stage functionalisation of the affibody Ac-Cys-ZEGFR:1907 (zEGFR) and the protein histone 2A (H2A). Given the overall simplicity and efficiency of the chemistry, we anticipate that the Cys functionalisation methodology reported here will find widespread application in the synthesis of high value peptide and protein conjugates in the future.

  1. C. Conibear, E. E. Watson, R. J. Payne and C. F. W. Becker. Chem. Soc. Rev. 2018, 47, 9046–9068.
  2. A. Hoyt, P. M. S. D. Cal, B. L. Oliveira and G. J. L. Bernardes, Nat. Rev. Chem. 2019, 3, 147–171.
  3. S. A. Byrne, M. J. Bedding, L. Corcilius, D. J. Ford, Y. Zhong, C. Franck, M. Larance, J. P. Mackay and R. J. Payne. Chem. Sci. 2021, 12, 14159-14166.