Cytochrome c oxidase from bakers’ yeast contains three mitochondrially made subunits (I to III) which are relatively hydrophobic and four cytoplasmically made subunits (IV to VII) which are relatively hydrophilic (Mason. T. L., Poyton, R. O., Wharton, D. C., and Schatz, G. (1973) J. Biol. Chem. 248, 1346-1354 and Poyton, R. O., and Schatz, G. (1975) J. Biol. Chem. 250, 752-761. In order to expl...

The effects of digitonin and tocopherol on bovine heart reduced diphosphopyridine nucleotideand succinate-cytochrome c reductases and cytochrome c oxidase have been studied with the following results. 1. Low concentrations of digitonin stimulate succinateand DPNH-cytochrome c reductase and cytochrome c oxidase. Higher concentrations of digitonin completely inhibit cytochrome c reductases, while...

Controlled osmotic lysis (water-washing) of rat liver mitochondria results in a mixed population of small vesicles derived mainly from the outer mitochondrial membrane and of larger bodies containing a few cristae derived from the inner membrane. These elements have been separated on Ficoll and sucrose gradients. The small vesicles were rich in monoamine oxidase, and the large bodies were rich ...

We previously reported that hepatocytes exhibit a reversible suppression of respiration during prolonged hypoxia (PO2 = 20 torr for 3-5 h). Also, isolated bovine heart cytochrome c oxidase undergoes a reversible decrease in apparent Vmax when incubated under similar conditions. This study sought to link the hypoxia-induced changes in cytochrome oxidase to the inhibition of respiration seen in i...

Recent studies on the chemical nature of cytochrome oxidase (cytochrome c :02 oxidoreductase, EC 1.9.3.1) have been concerned largely with the structure of its iron-porphyrin prosthetic group (cj. (l)), the importance of copper as an integral component of the enzyme (e.g. (2-5)), and the possible role of a lipid factor (e.g. (6-8)). By contrast, little work has been done on the nature of the fu...

Since the pioneer studies of Keilin and Hartree (l), considerable evidence has accumulated indicating that cytochrome c oxidase contains two heme moieties that react differently; hence the designation cytochrome U-Q. Reasons for this designat.ion include kinetic studies that show (a) differences in the rate of reduction and oxidation of cytochrome c oxidase measured at the a versus y absorption...