Fig. 3.

Kinetic parameters of AmPrβCD binding. (A) Higher positive voltages increase the probability to find the channel in a completely blocked state. The probabilities were found as the ratios of the total time spent by the channel in a blocked state to the total observation time. Fifty to 150 blocking events were analyzed, depending on the AmPrβCD concentration and applied voltage. Error bars show root-mean-square deviations of estimates obtained from three different fragments of the current record. (B) Typical statistical analyses of AmPrβCD-induced blockages performed by direct single-exponential (“log probability”) fitting of the residence time histograms (see ref. 31 for details of the method). The fits represent “variable metric” as a search method and “maximum likelihood” as a minimization method. Note the difference in the residence times for 0.75 and 2.5 M KCl. (C) Correlation between AmPrβCD residence time and KCl concentration at 100-mV applied voltage. The residence time is obtained by the single-exponential fitting as illustrated in B. Error bars represent root-mean-square deviations of estimates obtained by using different search, minimization, and weighting fitting methods available within the clampfit 9.2.0.10 program (Axon Instruments).