[Reversible electric current generation by reconstituted mitochondrial transhydrogenase].

A direct measurement of the electrogenic activity of purified mitochondrial transhydrogenase has been carried out. For this purpose beef heart transhydrogenase was isolated and reconstituted with phospholipids to form proteoliposomes. The transhydrogenase proteoliposomes were incorporated into a membrane filter impregnated with a decane solution of phospholipids. It was shown that the addition of substrates of either forward (NADPH and NAD+) or reverse (NADH and NADP+) transhydrogenase reaction gives rise to formation of electric potential difference across the proteoliposome-treated membrane filter. The electric vector depends on the direction of the reaction. The proteoliposome-supplemented compartment charges negatively in the case of the reverse one. The addition of the reaction products after substrate equalizes the potentials. The transhydrogenase-treated membrane retains the ability to the transhydrogenase-linked electrogenesis after removal of an excess of non-incorporated proteoliposomes.