Controlled Reversible N-Terminal Modification of Peptides and Proteins.

A reversible modification strategy enables a switchable cage/decage process of proteins with an array of applications for protein function research. However, general N-terminal selective reversible modification strategies which present site selectivity are specifically limited. Herein, we report a general reversible modification strategy compatible with 20 canonical amino acids at the N-terminal site by the palladium-catalyzed cinnamylation of native peptides and proteins under biologically relevant conditions. This approach broadens the substrate adaptability of N-terminal modification of proteins and shows a potential impact on the more challenging protein substrates such as antibodies. In the presence of 1,3-dimethylbarbituric acid, palladium-catalyzed deconjugation released native peptides and proteins efficiently. Harnessing the reversible nature of this protocol, practical applications were demonstrated by precise function modulation of antibodies and traceless enrichment of the protein-of-interest for proteomics analysis. This novel on/off strategy working on the N-terminus will provide new opportunities in chemical biology and medicinal research.