[Investigation of the effect of phospholipase on Na,K-ATPase activity]

Temperature dependence of bovine brain NA,K-ATPase before and after the short-term treatment of enzyme preparations with phospholipases A, C and D is investigated. Arrhenius plots of the temperature dependence of the reaction rate catalysed by Na,K-ATPase are non-linear, they have an inflection at the region of about 20 degrees C. The treatment of the enzyme with phospholipase A makes the inflection more smooth, phospholipase D shifts the inflection by 4 degrees C to lower temperature and simultaneously activates Na,K-ATPase. Phospholipase C sharply changes the Arrhenius curve and makes it linear. The data obtained are discussed with respect to the role of phospholipids in the formation of membrane bilayer and in the regulation of Na,K-ATPase activity.