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.     

Excess permittivities,excess refractive indices and NMR spectroscopic studies of solutions of 1,2-dibromoethane in aromatic hydrocarbons

Excess permittivities and excess refractive indices data for solutions of 1,2-dibromoethane (DBE) in benzene, toluene, o-xylene, m-xylene and p-xylene over the whole composition range at 25°C have been obtained. The analysis of excess dielectric properties suggests the existence of weak electron donor-acceptor type interactions between 1,2-dibromoethane (DBE) and aromatic hydrocarbons. The equilibrium constants and the dipole moments of the DBE-aromatic hydrocarbon complexes in solutions have been evaluated. Strneght of interaction increases with electron donating power of aromatic hydrocarbons. NMR spectroscopic studies made on these binary liquid systems also provide evidence for the existence of weak electron donor-acceptor type specific interactions between DBE and aromatic hydrocarbons.