Mg2+ and Ca2+ Activated ATPase Activities of Bovine Aortic Microsomes

Abstract

Microsomes from bovine aorta contained a Mg-activated or basic ATPase activity and a Ca-activated ATPase activity that was independent of Mg. Ca2+ stimulated Mg2+ dependent extra ATPase was not demonstrable. Kinetic analyses of the Mg basic ATPase and Ca ATPase activities suggested that the Mg activation and Ca activation of ATP hydrolysis probably represent a single enzyme moiety. The ATPase has equal affinity for Mg and Ca and does not distinguish between them.