[Effect of the structural integrity of Na,K-ATPase preparations on the ability of lithium to substitute for sodium in enzyme activation].
The ability of Li+ to substitute for Na+ in activating ouabain-sensitive ATPase of the rat kidney was studied on three kinds of the enzyme preparation: a) crude membrane fraction, b) purified enzyme, c) tissue slices. The preparations were free of endogenous Na+ and K+. The ATPase activity of slices was estimated both biochemically and cytochemically. In slices, the extent of Li+--Na+-isomorphism was about 10-fold higher than that in the purified enzyme. It is concluded that the biochemical procedures involved in the enzyme isolation procedure cause the damage of membranes, thus decreasing Li+-affinity to the Na+-dependent site.
D000818:Animals; D002414:Cations, Monovalent / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D007679:Kidney Medulla / Q000201:enzymology; D008094:Lithium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000302:isolation & purification / Q000378:metabolism*; D013329:Structure-Activity Relationship
D002414:Cations, Monovalent; D008094:Lithium; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase
Vliianie strukturnoĭ sokhrannosti preparatov Na,K-ATFazy na sposobnost' litiia zameshchat' natriĭ v aktivatsii fermenta.