RECONSTITUTION OF THE DINITROPHENOL-SENSITIVE ATP-ADP EXCHANGE REACTION OF OXIDATIVE PHOSPHORYLATION

Abstract

Addition of the 20-fold purified dinitrophenol-insensitive, soluble, mitochondrial ATP-ADP exchange enzyme to phosphorylating digitonin fragments of the mitochondrial membranes causes "recombina-tion" of the soluble enzyme to those sites in the energy-coupling mechanism, so that dinitrophenol-sensitivity of the ATP-ADP exchange is largely restored. The "recombination" occurs only if the particles are capable of oxidative phosphorylation; no conferral of dinitrophenol sensitivity occurs with aged particles or in the presence of azide. Other enzymes showing ATP-ADP exchange do not show dinitrophenol sensitivity. Purification of the ATP-ADP exchange enzyme to about 150-fold results in loss of the ability to "recombine"; it is suggested a second protein necessary for "rebinding" is lost during fractionation. The findings also indicate the feasibility of reconstituting the complex reactions of oxidative phosphorylation by combining soluble and insoluble elements in a specific manner.