title: pH regulation of divalent/monovalent Ca/K cation transport selectivity by a macrocyclic carrier molecule.
abstract: The lipophilic dicarboxylic acid-dicarboxamide macrocycle 1 is an efficient carrier for calcium and potassium transport through a liquid membrane. The process involves competitive Ca2+/K+ symport coupled to proton antiport in a pH gradient. It presents a very pronounced phenomenon of pH regulation of transport selectivity from preferential K+ transport to preferential Ca2+ transport as the pH increases from 2 to 9 in the starting aqueous phase containing the metal ions. The results demonstrate how carrier design allows control of the rate and selectivity of divalent/monovalent M2+/M+ cation transport.
mesh_terms: D002118:Calcium / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000138:chemical synthesis; D008566:Membranes; D011188:Potassium / Q000378:metabolism; D011522:Protons; D013329:Structure-Activity Relationship
chemical_list: D007476:Ionophores; D011522:Protons; D011188:Potassium; D002118:Calcium