Preparation and general properties of a soluble adenosine triphosphatase from mitochondria

Abstract

1. The purification of an adenosine triphosphatase present in aqueous extracts of acetone-dried ox-heart mitochondria is described. 2. No evidence was found for the presence of more than one protein having adenosine-triphosphatase activity in these extracts. 3. The enzyme is less stable at 0° than at 25° but is stabilized by glycerol. 4. The activity is dependent on the presence of Mg²⁺ or certain other bivalent metal cations. 5. The adenosine-triphosphatase activity of the Mg²⁺-activated enzyme is enhanced by 2,4-dinitrophenol. 6. The kinetics of Mg²⁺ activation indicate that the ATP–Mg²⁺ complex is the important substrate: free ATP and Mg²⁺ are inhibitory. 7. This preparation of mitochondrial adenosine triphosphatase has many properties in common with the adenosine triphosphatase coupling factor from mitochondria (Racker, 1961).