脂質二重層膜におけるX537Aによる担体イオン輸送機構

概要

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A theoretical treatment in terms of a carrier model is made to obtain a generalized equation for the BLM conductance produced by the charged complex formation between plural multivalent cations and plural charged carriers.<BR>The following experimental observations have been performed to deduce the ion transport mechanism across a BLM doped with Br-derivative of ionophore X537A (X-) according to the above-stated carrier model.The membrane conductance remarkably increases on the addition of X- to the aqueous solutions containing alkali metal cations.The membrane potential under a gradient of the concentration of monoor divalent cation shows quasi-Nernst behavior for the mono- or divalent cation, respectively.The ion conductance is proportional to approximately the square of the X- concentration, and it increases linearly with an increase in the ionic activities with a slope of 2 or 1 for the mono- or divalent cations, respectively, on a log-log plot.<BR>Thus it is concluded that the HX2- complex acts as a carrier for two alkali monovalent cations (I-) leading to a complex of I2HX2, and this carrier complex combines with one alkali divalent cation (12+) as well as with one hydrogen ion (H+) leading to a complex of IH2X22+.