<em>N</em>-vinyl acrylamides: Versatile heterobifunctional electrophiles for thiol–thiol bioconjugations — ASN Events
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  3. N-vinyl acrylamides: Versatile heterobifunctional electrophiles for thiol–thiol bioconjugations

N-vinyl acrylamides: Versatile heterobifunctional electrophiles for thiol–thiol bioconjugations (#207)

Marzieh Ahangarpour 1 , Iman Kavianinia 1 , Paul A. Hume 2 , Paul Harris 1 , Margaret Brimble 1
  1. School of Chemical Sciences, The university of Auckland, Auckland
  2. School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington

Site-selective chemical modification of peptides and proteins while preserving their function and structural integrity has emerged as a versatile and powerful tool to access invaluable multicomponent conjugates with a myriad of diverse applications such as drug delivery, medical diagnostics, live cell imaging, and molecular and cell biology.1–5 However, the presence of hundreds of potential active sites found in the sequences of native proteins renders selective modification of proteins at a specific residue challenging.6 Therefore, site-directed modification of the protein side chains relies on the ability to perform the modification with exquisite chemo- and regio-selectivity, under non-denaturing conditions.7

Cysteine has long attracted attention for site-selective protein modification due to its low abundance (1.7%). Moreover, the intrinsic nucleophilicity of a cysteine thiolate enables rapid reactivity with electrophiles to form thioethers under physiological conditions.1,8

We report the first examples of thiol-selective heterobifunctional electrophiles, N-vinyl acrylamides, that enable efficient highly selective thiol–thiol bioconjugations and cysteine modification of peptides and proteins. We demonstrate that these new classes of thiol-selective scaffolds can readily undergo a thia-Michael addition and an orthogonal radical induced thiol-ene “click” reaction under biocompatible conditions (Scheme 1A). Furthermore, the formation of an unexpected Markovnikov N,S-acetal hydrothiolation was explained using computational studies (Scheme 1B). We also reveal that N-methylation of the N-vinyl acrylamide scaffold changes the regio-selectivity of the reaction (Scheme 1C).

 We demonstrate that use of N-vinyl acrylamides shows promise as an efficient, mild, and exquisite cysteine-selective protocol for facile construction of fluorophore-labelled peptides and proteins and that the resultant conjugates are resistant to degradation and thiol exchange thus significantly improving their biophysical properties.

 

 

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  1. Ahangarpour, M.; Kavianinia, I.; Harris, P.; Brimble, M. Photo-Induced Radical Thiol-Ene Chemistry: A Versatile Toolbox for Peptide-Based Drug Design. Chem. Soc. Rev. 2021, 50(2), 898-944.
  2. Hoyt, E. A.; Cal, P. M. S. D.; Oliveira, B. L.; Bernardes, G. J. L. Contemporary Approaches to Site-Selective Protein Modification. Nat. Rev. Chem. 2019, 3(3), 147–171.
  3. Walsh, S. J.; Bargh, J. D.; Dannheim, F. M.; Hanby, A. R.; Seki, H.; Counsell, A. J.; Ou, X.; Fowler, E.; Ashman, N.; Takada, Y. Site-Selective Modification Strategies in Antibody–Drug Conjugates. Chem. Soc. Rev. 2021, 50(2), 1305–1353.
  4. Xue, L.; Karpenko, I. A.; Hiblot, J.; Johnsson, K. Imaging and Manipulating Proteins in Live Cells through Covalent Labeling. Nat. Chem. Biol. 2015, 11(12), 917–923.
  5. Krall, N.; Da Cruz, F. P.; Boutureira, O.; Bernardes, G. J. Site-Selective Protein-Modification Chemistry for Basic Biology and Drug Development. Nat. chem. 2016, 8(2), 103.
  6. deGruyter, J. N.; Malins, L. R.; Baran, P. S. Residue-Specific Peptide Modification: A Chemist’s Guide. Biochem. 2017, 56(30), 3863–3873.
  7. Spicer, C. D.; Davis, B. G. Selective Chemical Protein Modification. Nat. chem. 2014, 5(1), 1–14.
  8. Chalker, J. M.; Bernardes, G. J. L.; Lin, Y. A.; Davis, B. G. Chemical Modification of Proteins at Cysteine: Opportunities in Chemistry and Biology. Chem. Asian. J. 2009, 4(5), 630–640.
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