[Control of proton transport across the double electrical layers of mitochondrial membranes]

The effects of cardiolipin, dodecylsulfate anion and K+ on inhibition of respiration of intact and briefly frozen mitochondria by electrophylic compounds, e. g. beta-haloidalkylamines-p-(N,N-di-2-chlorethylamino)phenylacetic (I) and--phenylbutyric (II) acids were studied. It was shown that in K+-containing media the increase of the negative surface charge of the frozen mitochondrial membrane enhances the inhibition of mitochondrial respiration. In media without K+ this affect is absent. The inhibition of mitochondrial respiration by I and II is due to local increase of activity of the acids in mitochondrial membrane in the course of hydrolysis. It was assumed that the double electrical layers hamper the transport of the acid from the hydrophobic zone of the membrane into the environment including the water phase. Using this model, it was demonstrated that when the double electrical layer is destroyed, the inhibition of respiration by I is decreased at increased buffer capacity of the incubation medium. Correspondingly, in intact mitochondria the buffer capacity of the medium does not practically affect the inhibition of respiration by I.