Stimulation of Adenosine Triphosphatase Activity Mitochondria and Submitochondrial Particles

Crane and Lipmann (1) have shown that arsenate uncouples oxidative phosphorylation in intact rat liver mitochondria, and that this effect can be reversed by phosphate. They postulated that arsenate competes with phosphate at the site of phosphate uptake. It has also been observed that arsenate can stimulate the respiration of intact mitochondria (1) and of submitochondrial particles’ in the absence of phosphate and phosphate acceptor system. In view of the reversible nature of the transphosphorylation reactions of oxidative phosphorylation (2, 3)) it appeared reasonable to expect that arsenate should also bring about a stimulation of adenosine triphosphate hydrolysis in phosphorylating enzyme preparations. This communication demonstrates that arsenate stimulates the ATPase activity of intact rat liver mitochondria and of phosphorylating submitochondrial particles prepared by the digitonin method. This finding, together with other observations, suggests that arsenate brings about an “arsenolysis” of some intermediate in oxidative phosphorylation which normally is capable of reacting with inorganic phosphate.