[Catalytic properties of solubilized brain Na+,K+-ATPase].

The results are presented of a kinetic study of solubilized Na+, K+-ATPase obtained by 0.2+ digitonin from the NaI treated microsome fraction of the bull brain. It is shown that in main kinetic parameters (KmATP, V, pH-optimum, optimal [Na+]/[K+] ratio, etc.) the solubilized Na+, K+-ATPase does not differ essentially from membrane-bound enzyme. These results evidence for the absence of changes in principle for the kinetic behaviour of Na+,K+-ATPase when solubilized with digitonin. Simultaneously there are certain differences for a temperature dependence (the bend position in the Arrhenius anamorphosis) of the solubilized enzyme and its sensitivity to the action of strophanthin K.