Fig. 3: Effect of module type and additives on the electrostatic assistance of peptide thioester aminolysis.

a Reactions studied. Conditions: Peptide thioester 1 (5 mM), glycyl peptide 2 (5 mM), sodium hydrogen carbonate (50 mM)/CO₂ buffer, 37 °C, pH 7. b–d When the error is indicated, the data correspond to the mean and standard error for independent experiments (95% confidence interval). b Importance of the presence of complementary charged modules. 3a,a n = 4, 3d,a n = 3, 3a,g n = 4, 3d,g n = 4. c Effect of the number of Arg residues. 3a,a n = 4, 3a,e n = 3, 3a,f n = 3, 3a,g n = 4, otherwise, experiments were performed only once. d Effect of the number and position of pSer residues. 3a,a n = 4, 3b,a n = 3, 3c,a n = 3, 3d,a n = 3. e Effect of additives (6 M Gn·HCl, 6 M urea, see Supplementary Methods for more data). LC-MS of the crude reaction mixtures after 17 h. *Peptide thioester hydrolysis byproduct. f The effect of the ionic strength was studied by adding NaCl (I = 50–300 mM). The data for the reaction of peptide thioester 1a with glycyl peptide 2a were fitted to a pseudo first-order rate law (see Supplementary Methods). The errors for rate constants correspond to the standard error of the non-linear regression analysis to a first-order rate law (95% confidence interval).