Effect of Azide on the ATPase Activity of Isolated CF1

The effect of azide on M g2+-and Ca2+-dependent ATPase of differently activated CF1 isolated from spinach chloroplasts was studied. It is shown that Mg2+-ATPase activity is sensitive towards azide irrespective of the applied method of enzyme activation. Heat-or trypsin-acti-vated Ca2+-ATPase is also inhibited, whereas methanol-and octylglucoside-stimulated or DTT-activated Ca2+-ATPase is not affected by azide. Preincubation of the DTT-activated enzyme with low concentrations of Mg2+ induces azide susceptibility of the Ca2+-dependent ATPase.