biostudies-literatureSarkar SNational Institute of General Medical SciencesNIGMS NIH HHS2165-2178https://www.ebi.ac.uk/biostudies/studies/S-EPMC9526446biostudies-literatureUnknown17(8)The methylation of peptide backbone amides is a hallmark of bioactive natural products, and it also greatly modifies the pharmacology of synthetic peptides. Usually, bioactive <i>N</i>-methylated peptides are cyclic. However, there is very limited knowledge about how post-translational enzymes can be applied to the synthesis of designed <i>N</i>-methylated peptides or peptide libraries. Here, driven by the established ability of some RiPP enzymes to process diverse substrates, we sought to define catalysts for the <i>in vivo</i> and <i>in vitro</i> macrocyclization of backbone-methylated peptides. We developed efficient methods in which short, synthetic <i>N</i>-methylated peptides could be modified using side chain and mainchain macrocyclases, PsnB and PCY1 from plesiocin and orbitide bioACS chemical biologyApplying Promiscuous RiPP Enzymes to Peptide Backbone <i>N</i>-Methylation Chemistry.PMC9526446R35 GM122521R35GM122521Sarkar SSchmidt EWGu WfalseApplying Promiscuous RiPP Enzymes to Peptide Backbone <i>N</i>-Methylation Chemistry.The methylation of peptide backbone amides is a hallmark of bioactive natural products, and it also greatly modifies the pharmacology of synthetic peptides. Usually, bioactive <i>N</i>-methylated peptides are cyclic. However, there is very limited knowledge about how post-translational enzymes can be applied to the synthesis of designed <i>N</i>-methylated peptides or peptide libraries. Here, driven by the established ability of some RiPP enzymes to process diverse substrates, we sought to define catalysts for the <i>in vivo</i> and <i>in vitro</i> macrocyclization of backbone-methylated peptides. We developed efficient methods in which short, synthetic <i>N</i>-methylated peptides could be modified using side chain and mainchain macrocyclases, PsnB and PCY1 from plesiocin and orbitide bio2022-01-01T00:00:00Z2022 Aug2025-04-04T20:06:54.8Z2025-04-04T20:06:54.8ZS-EPMC95264463581906210.1021/acschembio.2c00293