Fig. 1: The effect of amide-to-ester substitution on the permeability of dipeptides. | Nature Communications

Fig. 1: The effect of amide-to-ester substitution on the permeability of dipeptides.

From: Amide-to-ester substitution as a stable alternative to N-methylation for increasing membrane permeability in cyclic peptides

Fig. 1

a General structures of model dipeptides. b Sequences of synthesized dipeptides. c Permeability values of the synthesized dipeptides measured by PAMPA. PAMPA was conducted with 10 μM compounds in 5% DMSO/PBS (pH 7.4) and 18 h incubation at 25 °C. Each bar represents the mean value, and the error bars the standard deviation from experiments carried out in quadruplicate. For P2, the peptides from the acceptor wells in two out of four trials were under the quantification limit, therefore the bar represents the mean value, and the error bars the standard deviation from experiments carried out in duplicate. P values were determined by a two-sided Welch’s t-test. **p < 0.01. p (P1 vs. D1) = 0.0007, p (D1 vs. M1) = 0.0007, p (P2 vs. D2) = 0.0017, p (D2 vs. M2) = 0.0072, p (P3 vs. D3) < 0.0001 and p (D3 vs. M3) < 0.0001.

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