[Adenosine triphosphatase from the membrane of Micrococcus lysodeikticus].

A preparation of ATPase with a high specific activity was isolated from the membrane of M. lysodeikticus. The enzyme was studied using UV-spectroscopy and circular dichroism. The homogeneity of the protein preparation was shown by gel electrophoresis. The catalytic properties of the enzyme were studied using steady state kinetic methods. The values of Km app. and kcat were determined to be 6-10(-4) and 6 mumoles/mg/min respectively. It is shown that ADP is an effective inhibitor of the ATPase reaction, and the inhibition activity increases in the presence of an excess of Ca2+. The nature of the rate dependence of the ATPase reaction on the concentration of the substrate and on Ca-ADP corresponds to a competitive type of inhibition with binding several molecules of Ca-ADP in the active site of the enzyme.