Sodium-Potassium-activated Adenosine Triphosphatase of Electrophorus Electric Organ

A magnesium-potassium-activated hydrolysis of p-nitrophenyl phosphate is catalyzed by a microsomal preparation from Electrophorus electric organs. The properties of this reaction are compared with those of the magnesium-sodium-potassium-activated hydrolysis of adenosine triphosphate which is catalyzed by the same preparations. Although superficially similar, a detailed comparison of the alkali metal activation of the two reactions indicates that they are catalyzed by distinct enzymes.