Figure 3. Ion currents and small molecule transport mediated by Pput2725.

(A) Ion current trace of three subsequent single channel insertions into a solvent free membrane of DPhPC at +250 mV applied voltage, each giving rise to a single conductance state of ~30 pA. The lower panel shows the ion current amplitude histogram of this trace, indicating in addition to the zero conductive state a distribution around three distinctive current states. The conductance value of each channel is ~126 pS. Experimental conditions are 1M KCl 10 mM MES pH 6 and T = 20 °C. (B) Current (I) vs. Voltage (V) curve of Pput2725. The I–V curve is obtained from at least four independent measurements. (C) Relative substrate uptake rates shown as ΔOD₄₀₀ values for the large-diameter OmpF porin from E. coli and for Pput2725. The following substrates were tested for Pput2725: glycine (G), glutamic acid (E), glutamine (Q), lysine (K), glucose and sucrose. Representative averages for 3–4 experiments are shown together with their standard deviations.