Abstract
The initial rate of the uptake of Pi, succinate, citrate and ketoglutarate, even at low concentrations, is not affected by uncouplers, when added simultaneously with the substrate at concentrations which uncouple oxidative phosphorylation and decrease substrate uptake at equilibrium. The first-order constant of succinate uptake is significantly increased by uncouplers. If, however, mitochondria are preincubated with uncouplers in order to collapse the ΔpH, the rate of substrate uptake is lowered. At high concentrations, of the same order of those used for the substrates, uncouplers have an inhibitory effect also when added together with the substrate. It is concluded that (a) the uncoupling effect is not related to the interaction of uncouplers with substrate carriers or to their entry on these transport systems, (b) the inhibition of substrate uptake at equilibrium can be accounted for only by the collapse of the ΔpH, (c) the interaction of high uncoupler concentrations with the substrate carriers is a secondary and unspecific effect.
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Prezioso, G., Palmieri, F. & Quagliariello, E. Kinetic study of the effect of uncouplers on substrate uptake by rat-liver mitochondria. J Bioenerg Biomembr 3, 377–385 (1972). https://doi.org/10.1007/BF01516076
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DOI: https://doi.org/10.1007/BF01516076