Studies on the content and organization of the respiratory enzymes of mitochondria.

(1) The mathematical calculations relating spectrophotometric data with the data of Allard et al. (4, 5) on mitochondrial counts, is presented. Such a calculation indicates that an "average mitochondrion" from rat liver would contain about 17,000 molecules of each cytochrome pigment. (2) Hematocrit determinations relating respiratory pigment content for mitochondria isolated from a variety of tissues have been presented, showing a fivefold variability depending upon the source of the mitochondria. (3) Speculations on the organization of the respiratory enzymes associated with the membrane structure of the mitochondria are discussed.