With a certain fixed methods of analyses, we carried out the determination of flavins and cytochromes in the mitochondria (Mt) and electron transfer particles (ETP) of the heart and liver of rats and cows, and made a comparison
of the data with one another. Our findings may briefly be summarized as follows. 1. The concentration of each component of the beef heart mitochondria proved to be 0.47 for acid extractable flavins; 0.22 for acid nonextractable
flavin; O. 75 for cytochrome (cyt.) a; 0.58 for cyt. b; and O. 51 for cyt. C + Cl, all units being mμ mole per mg of protein. 2. In the beef liver mitochondria it was 0.46 for acid extractable flavins; 0.18 for acid non-extractable flavin; 0.092 for cyt. a; 0.089 for cyt. b; and
0.122 for cyt. C+Cll likewise all units in term of mμ mole per mg of protein. 3. In the case of rat heart mitochondria, it was found to be O. 42 for acid
extractable flavins; 0.22 for acid non-extractable flavin; 0.88 for cyt. a; 0.41 for cyt. b; and 0.62 for cyt. C + Cll all in mμ mole per mg of protein.
4. In the rat liver mitochondria it was 0.56 for acid extractable flavins; 0.19 for acid non-extractable flavin; 0.20 for cyt. a; 0.14 for cyt. b; and 0.19 for cyt. C+Cl.
5. The concentration ratios of Fs, cyt. a and cyt. b of the mitochondria, what are considered to be intrinsic and fixed components of the mitochondrion. to those of the electron transfer particles were 1. 3 in both the beef heart and the rat heart, while 2.2 in the beef liver and 2.1 in the rat liver. 6. These findings were compared with the data reported by other workers, and also a discussion was made on the molecular organization of the mitochondrial
inner membrane.</p