Extended Data Fig. 4: Peptide stability and conversion in various Friedländer conditions.
From: Chemical and ribosomal synthesis of atropisomeric and macrocyclic peptides with embedded quinolines
a, Scheme of IVT reaction to produce peptides H2N-P1 and 2-P1, which were then exposed to either no reaction, AcOH at 40 °C for 24 h with no 2-aminoarylcarbonyl added, or AcOH at 40 °C for 24 h with 6 added. Extracted ion chromatogram (EIC) abundance for major ions of the starting material 2-P1 and product Q6-P1 (b), as well as the bystander peptide H2N-P1 (c). Bystander peptide H2N-P1 functions as an internal standard to demonstrate the stability of a nonreactive peptide under reaction conditions. AcOH reactions may result in mild degradation of 2-P1 but have little impact on H2N-P1. All reactions performed in triplicate, and all LC-HRMS measurements taken on the same day with the assumption that minimal changes in ionization efficiency occur during this timeframe. Error bars represent standard deviation (SD) d, Scheme showing reaction of IVT peptides with various 2-aminoarylcarbonyl substrates under three different Friedländer conditions. e, EIC abundance measurements show that Yb(OTf)3 reactions in organic solvents result in a more limited recovery of bystander peptide H2N-P1. EtOH conditions result in the complete disappearance of 2-P1, with a higher abundance of Q26-P1, while MeCN conditions show sizeable amounts of residual 2-P1 and a lower abundance of Q26-P1. All LC-HRMS measurements taken on the same day with the assumption that minimal changes in ionization efficiency occur across this timeframe. Note: experiments from a-c and d-e were performed separately with different batches of tRNA, IVT kit, monomer, and anti-FLAG magnetic beads and should not be directly compared.
