We report a sortase-based site-specific antibody–drug conjugation strategy, which involves an affinity peptide-directed acyl transfer reaction and sortase-mediated peptide ligation. Through the affinity peptide-mediated acyl transfer reaction, an LPXTG-containing peptide is conjugated to a specific Lys side chain of an antibody. Under the assistance of sortase, a protein drug bearing a GG motif reacts specifically with the LPXTG moiety to produce an antibody–drug conjugate. Our strategy for antibody conjugation can be applied not only to chemically synthesized drugs, but also to biologically expressed proteins, and will provide a new sortase-based strategy for the preparation of antibody–drug conjugates.
