Figure 4.

(A) Current traces representing the difference currents between control current and the currents blocked by 30 μM 4-sulphonic-calix[4]arene, -calix[6]arene and -calix[8]arene obtained from the data shown in Figure 1A. (B) Time constants of the difference currents, shown in A, as a function of voltage. The solid lines represent the fits of the data points to equation [2]. Best guesses for the parameters K_d(0), δ and k₁₀(0) were 59 μM, 0.31 and 12.5 s⁻¹ for 4-sulphonic-calix[4]arene, 77 μM, 0.23 and 4.8 s⁻¹ for 4-sulphonic-calix[6]arene and 86 μM, 0.17 and 4.9 s⁻¹ for 4-sulphonic-calix[8]arene. The value of the ratio k₁₂(0)/k₁₀(0) in the presence of calix[4]arene was 0.008, whereas it converged to zero in the presence of the other two compounds.