Activation parameters and molecular changes induced by substrate hydrolysis of the adenosine triphosphatase of Micrococcus lysodeikticus. A comparison of three different soluble forms of the enzyme

Summary The Arrhenius plots for the active and low activity soluble forms of the ATPase purified from the membranes ofMicrococcus lysodeikticus grown at 30°C presented discontinuities at 30 and 33°C, respectively. Their activation parameters differed, being highest for the low activity form of the enzyme.Both forms underwent changes in their molecular properties as a consequence of being enzymically active, i.e., upon incubation with substrates at an adequate temperature. These changes consisted of a decrease in the relative mobilities of some of their subunits in dodecyl sulphate polyacrylamide gel electrophoresis, and the temperature at which they occurred depended on the energy of activation of the particular form of the ATPase used. The low activity form required an incubation temperature of 50°C, whereas for an active form 37°C was sufficient.