Intramolecular methionine alkylation constructs sulfonium tethered peptides for protein conjugation

Continuous efforts were invested in selective modification of proteins. Herein, we first report the construction of sulfonium tethered cyclic peptides via an intramolecular cyclization by an aliphatic halide. This cyclization could enhance the stability and cellular uptake of peptides. Furthermore, the sulfonium center could be recognized by cysteine in the vicinity of the protein-peptide interacting interface and form peptide-protein conjugate.