Cation-activated ATPase activity of plasmalemma-enriched membrane preparations from maize coleoptiles

Abstract
The ATPase activity present in plasmalemma-enriched preparations from maize coleoptiles shows an optimum at pH 6, a strong dependence on Mg2+, and is stimulated by K+ and other monovalent cations, both organic and inorganic. The activation of ATPase by K+ obeys Michaelis Menten kinetics, saturation being reached at 50 mM K+ concentration. K+, Mg2+-stimulated ATPase activity is strongly inhibited by N,N′-dicyclohexylcarbodiimide and by diethylstilbestrol and, to a lesser extent, by octylguanidine.