Victor Laserna, Daniel Abegg, Cláudia Afonso,Esther Martin,Alexander Adibekian, Peter Ravn, Francisco Corzana, Gonçalo J. L. Bernardes
Angewandte Chemie International Edition 2021
https://doi.org/10.1002/anie.202108791
We describe maleic-acid derivatives as robust cysteine-selective reagents for protein labelling with comparable kinetics and superior stability relative to predominantly used maleimides. Diamide and amido-ester derivatives proved to be efficient protein-labelling species with a common mechanism in which a spontaneous cyclization reaction occurs upon addition to cysteine. Introduction of chlorine atoms in their structures triggers ring hydrolysis or further conjugation with adjacent residues, which results in conjugates that are completely resistant to retro-Michael reactions in the presence of biological thiols and human plasma. By controlling the microenvironment of the reactive site, we can control selectivity towards the hydrolytic pathway, forming homogeneous conjugates. The method is applicable to several scaffolds and enables conjugation of different payloads. The synthetic accessibility of these reagents and the mild conditions required for fast and complete conjugation together with the superior stability of the conjugates makes this strategy an important alternative to maleimides in the bioconjugation toolbox.
