Light scattering changes linked to oxidative phosphorylation in mitochondrial membrane fragments.

A close correlation between the process of oxidative phosphorylation and mitochondrial swelling and shrinking has been described by a number of investigators by means of light scattering measurements (l-lo). The effects of various reagents on mitochondrial volume have also been reported; some examples are: Ca++, phosphate, arsenate, adenine nucleotides, thyroxine, and agents which uncouple oxidative phosphorylation (2-5, 7-10). It is thought that the action of these agents is localized at the mitochondrial membrane which contains the electron transport system and the enzymes of oxidative phosphorylation. Since the mechanism by which mitochondrial swelling and shrinking take place are not yet known, it was of interest to determine whether mitochondrial membrane fragments (11) would be useful in clarifying the origin and mechanism of the swellingshrinking phenomenon at a macromolecular level. This article reports on the relationship between the activity of the phosphorylating respiratory chain and structural changes in mitochondrial membrane fragments.