Studies on the reconstitution of the structure and function of the mitochondrial inner membrane. II. Dissolution and reconstitution of the mitochondrial inner membrane

1) In order to study the molecular structure and electron transfer activities of mitochondrial inner membrane, dissolution and reconstitution of membranous structure and function of the inner membrane of beef heart mitochondria were carried out. 2) The inner membrane of mitochondria could be dissolved into some unit of particles 70-140 Å in diameter by the treatment with bile salts at the concentration 0.5 mg of deoxycholate per mg of protein, 0.5 mg of cholate per mg of protein and 74.5 mg of crystalline potassium chloride per ml of the suspension. 3) The dissolved unit particles readily reaggregated into a vesicular membrane simultaneously restoring over-all electron transfer activities by the removal of bile salts with dilution of the suspension.4) Isolated electron transfer unit particle fraction contammg all components of the electron transfer chain but no structural protein were soluble in aqueous solution due to some residual bile salts used in the preparation. The removal of bile salts by dilution led the dispersed particles to aggregate into membrane and restore their over-all enzymatic activities. 5) From these results and the results of the reconstitution of membrane from purified complexes as described in the previous paper, it may be concluded as follows: The mitochondrial inner membrane may consist of several kinds of repeating unit particles conjugating each other with adjacent particles. It is necessary for over·all enzymatic activities that some unit components aggregate into a single vesicular membrane. Structural proteins may play an important role in the constitution of the membranous structure and in the over-all enzymatic activities.