title: Determination of stability constants of valinomycin complexes with ammonium and alkali metal ions by capillary affinity electrophoresis.
abstract: Capillary affinity electrophoresis (CAE) has been employed to investigate quantitatively the interactions of valinomycin, macrocyclic depsipeptide antibiotic ionophore, with univalent cations, ammonium and alkali metal ions, K(+), Cs(+), Na(+), and Li(+), in methanol. The study involved measuring the change in effective electrophoretic mobility of valinomycin while the cation concentrations in the BGE were increased. The corresponding apparent stability (binding) constants of the valinomycin-univalent cation complexes were obtained from the dependence of valinomycin effective mobility on the cation concentration in BGE using a nonlinear regression analysis. The calculated apparent stability constants of the above-mentioned complexes show the substantially higher selectivity of valinomycin for K(+) and Cs(+) ions over Li(+), Na(+), and NH(4)(+) ions. CAE proved to be a suitable method for the investigation of both weak and strong interactions of valinomycin with small ions.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Sille
authors.initials: S
authors.lastname: Ehala
authors.forename: Václav
authors.initials: V
authors.lastname: Kasicka
authors.forename: Emanuel
authors.initials: E
authors.lastname: Makrlík
mesh_terms: D000468:Alkalies / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry; D002414:Cations, Monovalent / Q000737:chemistry; D004355:Drug Stability; D019075:Electrophoresis, Capillary / Q000379:methods*; D007476:Ionophores / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D014634:Valinomycin / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000468:Alkalies; D000900:Anti-Bacterial Agents; D002414:Cations, Monovalent; D007476:Ionophores; D000644:Quaternary Ammonium Compounds; D014634:Valinomycin