[Mechanism of coupling of ion transport and ATP hydrolysis in the Na-pump].
A generalized scheme of the reaction pathways during activation of the Na,K-ATPase by sodium and potassium ions and a relevant molecular model of the Na-pump are proposed. The model suggests light and heavy enzyme subunits possessing cavities with ion exchange sites. The cavities are of limited size and can contain only 3 sodium or 2 potassium ions. Free energy of ATP hydrolysis is expended on the formation of a special transient nonequilibrium enzyme conformation. In this conformation ion exchange between the subunit cavities becames possible. Na-pump operates as an enthropy machine: the ion movement across the membrane is provided by thermal oscillations of the subunits.
D001665:Binding Sites; D002463:Cell Membrane Permeability; D055598:Chemical Phenomena; D002621:Chemistry; D006868:Hydrolysis; D008954:Models, Biological; D008968:Molecular Conformation; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase; D013816:Thermodynamics
D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium
Mekhanizm sopriazheniia transporta ionov i gidroliza ATP v Na-nasose.