Supplementary Fig. 12: Discrimination of L_R7 and I_R7 under optimized recording conditions.

Histograms of relative residual current I_b/I₀ measured using a low-noise setup (see Supplementary Note 3). The nanopore experiments were performed using an equimolar mixture of L_R7 and I_R7 peptides and under the following experimental conditions: –50 mV in 4M KCl (a, n = 3474 events); –40 mV in 4M KCl (b, n = 2373 events); –40 mV in 2M KCl/2M KNO₃ mixture (c, n = 3437 events). In 4M KCl, the diminution of the voltage magnitude from –50 mV to –40 mV leads to a reduction of the standard deviations of the two main populations, and a shift of the I_b/I₀ values from 0.380 ± 0.0018 to 0.378 ± 0.0013 (L_R7) and from 0.384 ± 0.0016 to 0.382 ± 0.0012 (I_R7). At –40 mV, the substitution of 50% of the Cl^– ions by 50% of NO₃^– ions further reduces the standard deviations of the two main populations now located at I_b/I₀ values of 0.382 ± 0.0010 (L_R7) and 0.386 ± 0.0010 (I_R7). Continuous lines show the underlying Gaussian distributions. The mean value (respectively uncertainty) of relative residual current of each peptide was obtained as the mean value (respectively standard deviation) of a gaussian fit of the corresponding I_b/I₀ distribution; from single independent experiments. The data were acquired at room temperature and under a voltage bias applied to the trans compartment.