We report an
Fmoc-compatible and external-thiol-free method of peptide C-terminus
thioesterification with cysteinylprolyl imide. The newly synthesized structure,
i.e., cysteinylprolyl-thiazolidinone, provided high conversion and
sequence-independent fast kinetics (90 min) in the diketopiperazine thioester
formation under relatively mild conditions: pH 6.0, 37 °C. Employing this thioesterification method, we
synthesized histone H3.2 bearing K56 acetylation.