Electrogenic transport by lipophilic guanidinium salts as anion carriers in bilayer membranes |
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Authors: | Phillip M Danby Christie Lombardi Michael Meanwell |
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Institution: | Department of Chemistry, University of Victoria, Victoria, Canada |
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Abstract: | Anion transport by four isomers of tetradecylguanidinium in vesicle bilayer membranes was investigated by ion-selective electrode and pH-sensitive fluorescence methods. On a macroscopic scale, these carriers mediate hydroxide-anion antiport. In the absence of an externally imposed ionic gradient, the carriers produce a pH gradient due to rapid partition-deprotonation of the carrier and diffusion of the guanidine conjugate base. The formally coupled anion transport is slow relative to this process, and the system exhibits a corresponding membrane polarisation detected with potential-sensitive fluorescent dyes. Selective anion transport in competition with the efficient hydroxide transport is detected only with relatively easily extracted anions and N,N′-disubstituted isomers. Membrane polarisation changes can be deduced from simple equivalent circuits derived from the Goldman–Hodgkin–Katz voltage equation. |
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Keywords: | Membrane transport anion antiport electrogenic transport bilayer membrane |
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