Selective N-terminal modification of peptides and proteins using acyl phosphates

The selective modification of proteins and peptides is an important chemical biology tool with a wide variety of applications, including the production of biopharmaceuticals or the study of post-translational modifications. In particular, the selective acylation of the N-terminus over side chains in peptides and proteins is a highly desirable but challenging reaction in this field. Current methods have a range of shortcomings, including lack of selectivity or narrow substrate scope. Here we report a biomimetic approach using the in situ enzymatic reagent activation (ERA) of carboxylic acids with ATP to generate acyl-adenosine monophosphates. This method displays high selectivity for the N-termini of peptides and proteins, including pharmaceutically relevant liraglutide, glucagon and insulin. The ERA acylation tolerates a broad range of unsubstituted and substituted fatty acids, including azido and dicarboxylic acids, thus making it suitable for N-terminal bioorthogonal labelling strategies. Moreover, this strategy can also be applied to the modification of antibodies. In general, the ERA acylation is a versatile and bioorthogonal method that we envisage finding wider applications in the field of bioconjugation and the production of stable peptide and protein conjugates.