STUDIES ON MECHANISM OF STIMULATION OF GLYCOLYSIS AND RESPIRATION BY K+ IN SACCHAROMYCES CEREVISIAE

1. The effect of K+ on the respiration and glycolysis of yeast was investigated. Measurement of the levels of ADP, ATP and Pi revealed that K+ stimulates an enzymatic activity that diminishes ATP and increases ADP. This increase in the ADP level seems to be the responsible for the stimulation of both glycolysis and respiration. 2. When glucose was used as substrate, the increase in the levels of Pi upon the addition of K+ was found to be greater than either the ATP decrease or the ADP increase. This might mean that the ion induces the breakdown of ATP by an indirect mechanism, with another phosphorylated compound being hydrolyzed directly. The amount of ATP would decrease at the rate at which it was used to replace this hypothetical compound. 3. The studies on the mechanism by which K+ induces the stimulation of glycolysis and respiration suggest that it is the presence of the ion inside the cell or some consequence of this that induces the changes necessary to produce the stimulation of ATPase" activity responsible for the activation of glycolysis and respiration. The possibility that the presence of the ion outside the cell or the energy required for its transport causes the changes appears to have been eliminated. © 1969."