Purification and properties of membrane-bound coupling factor-latent ATPase from Mycobacterium phlei

The membrane bound coupling factor-latent ATPase was solubilized from the membrane vesicles of Mycobacterium phlei by using 0.25 M sucrose or low ionic strength buffer. Purification of the solubilized enzyme by use of Sepharose-ADP conjugate gel yielded a homogenous preparation of latent ATPase which was purified about 216-fold in a single step with an 84% yield. The enzyme exhibits a specific activity of 39 mumoles of ATP hydrolyzed per min per mg protein. The purified enzyme exhibits coupling factor activity. Electrophoresis in two dissociating solvent systems indicates that the enzyme contains at least three major polypeptides of molecular weights 56,000, 51,000, and 46,000 daltons, and two minor polypeptides of 30,000 and 17,000 daltons. Equilibrium binding studies of ADP with purified coupling factor-latent ATPase reveal the presence of two nucleotide binding sites per molecule with an apparent Ka of 8.1 X 10(-5) M. By use of affinity chromatography, another latent ATPase has been isolated from the solubilized enzyme, which does not exhibit coupling factor activity.