Oxidative phosphorylation and respiratory control in digitonin fragments of beef heart mitochondria.

The objective of the present study was to obtain large amounts of submitochondrial fragments which would carry out oxidative phosphorylation with only a few substrates. It was the desire of the authors to have a system as free of other reaction sequences and with as little extraneous material as possible in order to study the mechanism of the reactions involved in oxidative phosphorylation. Several methods have been published on the preparation of submitochondrial fragments which carry out electron t,ransport or oxidative phosphorylation. Cooper and Lehninger (1) and Devlin and Lehninger (2) have reported a method for obta.ining phosphorylating particles from liver mitochondria, and Ziegler et al. (3,4) have described a particle from beef heart mitochondria which possesses some phosphorylation activity. None of these preparations appeared to be entirely suitable for our experiments, so a method was developed for isolating large amounts of submitochondrial fragments, from beef heart mitochondria, which carry out oxidative phosphorylation with certain substrates and show some degree of respiratory control. A preliminary report of this work has been made (5).