[Effect of gangliosides on Na-K-ATPase activity and the conformation of microsomal membranes].

The effect of gangliosides on the activity of Na, K-ATPase and K-dependent nitrophenyl-phosphatase was studied. Low concentrations of gangliosides proved to activate Na, K-ATPase, and high ones to inhibit it. All the concentrations of gangliosides produced only an inhibitory effect on the K-dependent nitrophenyl-phosphatase. Inhibition of the enzyme by gangliosides is reversible and competitive in respect to K+. Calculation of Hill's coefficient demonstrated that both in case of the activating and of the inhibitory action gangliosides acted allosteric effectors. To ascertain the action mechanism of gangliosides on the enzyme their effect on the microsomal membranes was studied by the fluorescent probe method. Gangliosides were found to produce marked conformation shifts in the membranes of the brain microsomes.