Mutual inactivation of valinomycin and protonophores by complex formation in liposomal membranes

Abstract

The simultaneous presence of a protonophore [3,5-di(tert-butyl)-4-hydroxybenzylidenemalononitrile or carbonyl cyanide m-chlorophenylhydrazone] and valinomycin in a liposome suspension results in time-dependent inactivation of ion transport by both the protonophore and valinomycin. Correlation of the inactivation with spectrophotometric observations on the formation of a complex between the protonophore and valinomycin strongly suggests that the complex observed has no (or very low) activity for the transport of either H⁺ or K⁺. The stoichiometry of valinomycin and the protonophore in the inactive complex is shown to be 1:1.