ATP/ADP exchange activity of gastric (H+ +K+)-ATPase.

  title={ATP/ADP exchange activity of gastric (H+ +K+)-ATPase.},
  author={Edd C. Rabon and George Sachs and Sven M{\aa}rdh and Bj{\"o}rn Wallmark},
  journal={Biochimica et biophysica acta},
  volume={688 2},
The ATP/ADP exchange is shown to be a partial reaction of the (H+ +K+)-ATPase by the absence of measurable nucleoside diphosphokinase activity and the insensitivity of the reaction to P1, P5-di(adenosine-5') pentaphosphate, a myokinase inhibitor. The exchange demonstrates an absolute requirement for Mg2+ and is optimal at an ADP/ATP ratio of 2. The high ATP concentration (K0.5=116 microM) required for maximal exchange is interpreted as evidence for the involvement of a low affinity form of… CONTINUE READING