Tyrosine-Triazolinedione Bioconjugation as Site-Selective Protein Modification Starting from RAFT-Derived Polymers

The electrophilic aromatic substitution (SEAr) reaction of triazolinediones (TADs) with the phenol moiety of tyrosine amino acid residues is a potent method for the site-selective formation of polymer–protein conjugates. Herein, using poly(N,N-dimethylacrylamide) (pDMA) and bovine serum albumin (BSA) as model reagents, the performance of this tyrosine-TAD bioconjugation in aqueous solutions is explored. At first, reversible addition–fragmentation chain transfer (RAFT) polymerization with a functional urazole, a precursor for TAD, chain transfer agent is used for the synthesis of a TAD end-functionalized pDMA. Eventually, the BSA ligation efficiency and selectivity of this polymer was evaluated in different aqueous solvent mixtures using SDS-PAGE and mass spectroscopy after trypsin digestion.