CYTOCHEMICAL STUDIES OF MITOCHONDRIA

Abstract
Mitochondria isolated from rat liver were disrupted with 0.3% deoxy-cholate and a number of subtractions were isolated from this preparation by differential centrifugation. The protein N, RNA and phospho-lipide content, as well as the succinoxidase, cytochrome c oxidase, adenylate kinase, and DPNH-cytochrome c reductase of these fractions were determined. Two of these subtractions, found to consist of mito-chondrial membranes, contained-12% of the protein N and-35% of the phospholipide of the whole mitochondria and accounted for 70% of the succinoxidase and cytochrome c oxidase activity of the original mito-chondrial preparation. There was no discernible adenylate kinase, DPNH-cytochrome c reductase, or phosphorylating activities in these fractions, nor could they oxidize other substrates of the Krebs cycle. The most active fraction (60 minutes at 105,000 g pellet) had a higher phospholipide/protein value than the whole mitochondria and showed a seven- to elevenfold concentration of succinoxidase and cytochrome c oxidase activities. Evidence indicates that the various components of the succinoxidase complex are present in this membrane fraction in the same relative proportions as in the whole mitochondria. The implications of these findings are discussed.
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