Fig. 2.

Binding constants for asparagine binding to SBD1. a Current traces and all-point current histograms showing the binding of asparagine to SBD1 (120 nM, cis) inside a ClyA nanopore. Asparagine was added to the trans solution and the voltage was set to −90 mV. b Dependency of the opening and closing rates (calculated from the inverse of the dwell times) on the concentration of asparagine in the trans solution. The black and blue lines are linear fits. c Dependency of the percentage of the closed configuration on the concentration of asparagine in the trans solution. The blue line indicates fitting to a Hill function with the Hill coefficient set to one. The solution used for the electrical recording contained 150 mM NaCl, 15 mM Tris-HCl, pH 7.5. Current traces were collected applying a Bessel low-pass filter with a 2 kHz cutoff and sampled at 10 kHz at room temperature (25 °C). A post-acquisition Gaussian filter of 200 Hz was applied. Error bars represent the standard deviation between independent experiments (N = 3)