Enzymic activities of solubilised and dissociated (α + ß) chains and of soluble αß protomers of pig kidney Na⁺/K⁺-ATPase

Abstract

Two important issues about the sodium pump concern the subunit organisation of the active form(s) of the enzyme. One would like to know whether the membrane-bound enzyme is protomeric or dimeric, and also to decide whether the intact ß chain has a functional role in the reaction. As a first step, it seems necessary to define the catalytic potential of different subunit arrangements and detergent solubilisation of Na⁺/K⁺-ATPase in active form has been a fruitful approach to the question. This offers not only the possibility of manipulating the subunit composition but also of being able to characterise the resulting particles with the analytical ultracentrifuge on the basis of sound physical principles¹⁴.