The interaction of MgADP with H⁺‐ATPase in rat liver mitochondria

Abstract

The activating anions are found to induce an unexpectedly high (up to 8-fold for sulphite) increase of ATPase activity in intact rat liver mitochondria. This effect is not determined by the observed changes in Km and Ki (ADP) values. The stimulation seems to be caused by dissociation of the inactive complex of ATPase with Mg.ADP. The quantity of this complex formed in the course of ATP hydrolysis is approx. 90% of the total ATPase content in intact mitochondria. The data on toluene-permeabilized mitochondria suggest that the high content of the complex is a result of the stabilizing effect of some matrix macromolecules.