Protein conjugation by electrophilic alkynylation using 5-(alkynyl)dibenzothiophenium triflates

Published on July 7th, 2021

Authors: Victor Laserna, Alena Istrate, Kevin Kafuta, Tuuli A. Hakala, Tuomas P. J. Knowles, Manuel Alcarazo, and Gonçalo J. L. Bernardes

Bioconjugate Chem. 2021, Article ASAP. DOI: 10.1021/acs.bioconjchem.1c00317


5-(Alkynyl)dibenzothiophenium triflates are introduced as new reagents to prepare different protein conjugates through site-selective cysteine alkynylation. The protocol developed allows a highly efficient label of free cysteine-containing proteins with relevant biological roles, such as ubiquitin, the C2A domain of Synaptotagmin-I, or HER2 targeting nanobodies. An electrophilic bis-alkynylating reagent was also designed.

The second alkynylating handle thus introduced in the desired protein enables access to protein–thiol, protein–peptide, and protein–protein conjugates, and even diubiquitin dimers can be prepared through this approach. The low excess of reagent needed, mild reaction conditions used, short reaction times, and stability of the S–C(alkyne) bonds at physiological conditions make this approach an interesting addition to the toolbox of classical, site-selective cysteine-conjugation methods.

InstrumentFluidity One-W
Therapeutic area: reagents, peptides and proteins, monomers, addition reactions

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