Partial Resolution of the Enzymes Catalyzing Oxidative Phosphorylation

Abstract

Abstract 1. Submitochondrial particles have been sequentially treated with trypsin, urea, and sonic oscillation at an alkaline pH. These TUA particles required addition of a protein (Fc1) in order to render added ATPase (F1) sensitive to dicyclohexylcarbodiimide. Further resolution was obtained by exposure of TUA particles either to 2 m sodium thiocyanate or to 1.5% silicotungstate. These procedures removed a second soluble protein component (Fc2) which was also required for the sensitivity of ATPase to dicyclohexylcarbodiimide. 2. Preparations of Fc2 purified from the sodium thiocyanate extract stimulated the 32Pi-ATP exchange reaction and oxidative phosphorylation in silicotungstate-treated submitochondrial particles. 3. Treatment of TUA particles with silicotungstate reduced their ability to bind ATPase (F1). Addition of Fc2 restored the ability to bind ATPase. It is therefore proposed that Fc2 is a component which links the mitochondrial ATP-ase to the inner mitochondrial membrane.