Electrochemical Modification of Polypeptides at Selenocysteine — ASN Events
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  2. Poster Session 1 - Wine Tasting
  3. Electrochemical Modification of Polypeptides at Selenocysteine

Electrochemical Modification of Polypeptides at Selenocysteine (#293)

Angus Mackay 1 2 , Joshua Maxwell 1 2 , Max Bedding 1 2 , Sameer Kulkarni 1 2 , Stephen Byrne 1 2 , Lucas Kambanis 1 2 , Lara Malins 3 4 , Anneliese Ashhurst 2 5 , Leo Corcilius 1 2 , Richard Payne 1 2
  1. Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, NSW, Australia
  2. School of Chemistry, The University of Sydney, The University Of Sydney, NEW SOUTH WALES, Australia
  3. dAustralian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Australian National Uni-versity, Canberra, ACT
  4. Research School Of Chemistry, Australian National University, Canberra
  5. School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, Sydney

It is estimated that >70% of human proteins are posttranslationally modified with a vast array of different functionalities following ribosomal synthesis.1-3 Structurally, these posttranslational modifications (PTMs) vary widely, including the addition of individual functional groups, other polypeptides or biomolecules, as well as cleavage and cyclisation events.1-3 Functionally, PTMs have roles in the modulation of protein structure, activity and protein-protein interactions, greatly diversifying nature’s chemical repertoire outside of the proteinogenic amino acids. Given the importance of PTMs, the burgeoning field of protein therapeutics has sought to capitalise on these and other protein modifications to improve the properties of its frontline ‘biologics’.2

 

Progress towards investigating the effects of discrete PTMs, however, has been hampered by a lack of methods for accessing homogeneously modified biomolecules in pure form.4 In particular, existing bioconjugation methods for the late-stage functionalisation of proteins are hampered by inadequate conversions, poor kinetics, and limited biocompatibility and selectivity. With the limitations of current bioconjugation strategies still yet to be fully addressed, mild reaction manifolds such as electrochemistry present exciting opportunities for developing novel reactions which may be employed for the late-stage, selective modification of these biomolecules.

 

We have recently developed a novel electrochemical approach for achieving the mild and selective functionalisation of polypeptides. This methodology utilises the unique reactivity of the 21st amino acid, selenocysteine, to effect formation of valuable bioconjugates through redox-stable selenoether linkages, proceeding via formal extrusion of a selenium atom from the respective diselenide starting material. The novel reaction manifold was optimised for the rapid and targeted dimerisation and functionalisation of peptide substrates under mild and biocompatible conditions. The power of this electrochemical platform was then showcased through the late-stage C-terminal modification of the FDA-approved cancer drug leuprolide, and assembly of a library of anti-HER2 affibody-conjugates bearing complex cargoes. Following assembly by e-SE, the utility of functionalized affibodies for in vitro imaging and targeting of HER2 positive breast and lung cancer cell lines was also demonstrated.

  1. Walsh, C. T.; Garneau-Tsodikova, S.; Gatto Jr., G. J. Angew. Chem. Int. Ed. 2005, 44 (45), 7342-7372.
  2. Walsh, G.; Jefferis, R. Nat. Biotechnol. 2006, 24 (10), 1241-1252.
  3. Conibear, A. C. Nat. Rev. Chem. 2020, 4, 674–695.
  4. Barber, K. W.; Rinehart, J. Nat. Chem. Biol. 2018, 14 (3), 188-192.
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