Sodium-Potassium-activated Adenosine Triphosphatase

Activation of K+-dependent p-nitrophenylphosphatase activity occurs concurrently with inhibition of Na+-K+-ATPase activity when either glycerol or dimethyl sulfoxide is added to the reaction medium. The effects on both activities are reversible. The Na+-dependent ADP-ATP phosphotransferase reaction and K+-dependent acetyl phosphatase activities are also inhibited by dimethyl sulfoxide. The effects of these solvents are consistent with a decreased interaction of phosphokinase and phosphatase sites with the phosphoryl acceptor site and an increased accessibility of p-nitrophenylphosphate to the phosphatase site.