Effect of monovalent cations on the adenosinetriphosphatase of sonicated erythrocyte membrane

Abstract

• 1.

  1. Human erythrocyte membrane contains a Mg²⁺-dependent adenosinetriphosphatase activity. The enhancement of this activity requires the simultaneous presence of Na⁺ and K⁺. When the membranes were broken by ultrasonic vibrations, the adenosinetriphosphatase activity was enhanced with either Na⁺ and K⁺, and in this case enhancement was no longer affected by ouabain.

• 2.

  2. The effects of Mg²⁺, Ca²⁺, pH, and detergents on the various manifestations of the adenosinetriphosphatase activity, namely: (a) the Na⁺-plus-K⁺-dependent form, (b) the single-ion-dependent form, and (c) the ion-independent form, were studied. The results did not suggest the presence of more than one enzyme.

• 3.

  3. Since the single-ion-dependent adenosinetriphosphatase activity was revealed merely by a physical change in the method of preparation (sonication), it is reasonable to suspect that it and the Na⁺-plus-K⁺-dependent activity are different manifestations of a single enzymic activity.