ATP synthesis by the (Na+ + K+)-ATPase in the absence of an ionic gradient Effects of organic solvent

AbstractA 200-fold decrease in the Pi concentration required for half-maximal phosphorylation of the (Na+ + K+)-ATPase is observed when 40% (v/v) dimethyl sulfoxide is added to the assay medium. The phosphoenzyme formed in the presence of dimethyl sufoxide is able to transfer its phosphate to ADP to form ATP when 400 mM NaCl is added to the medium. The synthesis of ATP depends on the concentrations of organic solvent and of Na+, and is inhibited by ouabain