Mitochondria adrenal cortex

Adrenodoxin. Adrenodoxin is the only iron-sulfur protein which has been isolated from mammals. This protein from mitochondria of bovine adrenal cortex was purified almost simultaneously by Kimura and Suzuki (32) and Omura et al. (33). It has a molecular weight of 12,638 (34) and the oxidized form of the protein shows maximal absorbances at 415 and 453 nm. Adrenodoxin acts as an electron carrier protein in the enzyme system required for steroid hydroxylation in adrenal mitochondria. In this system, electron transfer is involved with three proteins cytochrome P. gQ, adrenodoxin and a flavoprotein. Reduced NADP gives an electron to Tne flavoprotein which passes the electron to adrenodoxin. Finally, reduced adrenodoxin transfers the electron to cytochrome Pas shown in Fig. 3. The mechanism of cytochrome P cq interaction with steroid, oxygen and adrenodoxin in mixed-function oxidase of adrenal cortex mitochondria has been reviewed by Estabrook et al. (35). 

The 2 Fe 2S plant type ferredoxins, MW 12,000 dal ton, Em = —430 mV, were first isolated from chloroplast and photosynthetic bacteria. Similar proteins have been purified from the bacteria E. coli (264) and Pseudomonas putida [ putidaredoxin , Em7 = —235 mV, (275)] and from mammalian adrenal cortex mitochondria [ adrenodoxin Em = — 367 mV, 13,100 dalton (165)] among other sources. 

Wang, H. P., Pfeiffer, D. R., Kumura, T., and Teheu, T. T., Phospholipids of adrenal cortex mitochondria and the steroid hydroxylase The lipid environment of cytochrome P-450. Biochem. Biophys. Res. Commun. 57, 93-99 (1974). 

Lambeth JD, Seybert DW, Lancaster JR, Salerno JC, Kamin H. Steroidogenic electron transport in adrenal cortex mitochondria. Mo/. Cell Biochem. 1982 45 13-31. 

In order for the heme to combine with such ligands as oxygen and carbon monoxide, one electron must be introduced to form the ferrous state (Peterson et a/., 1977). The oxidation-reduction step has been measured for the purified cytochrome P450 from adrenal cortex mitochondria and from P auaomorm putida. In each case large negative values have been obtained and correlated with the reductive titration of cytochrome P450 in rat liver microsomes (Cooper et a/., 1977). 

Flo. 2. (A) A nutochondrion isolated from rat liver, and negatively stained with isotonic ammonium molybdate. The negative stain penetrates the outer membrane, and within the cristal infoldings (dark areas), which appear to be poorly developed. Very few dark areas are visible within die proffle of the inner membrane. Note the spherical appearance of the organelle. (B) A mitochondrion isolated from rat kidney cortex and treated as in (A). The organelle is sphnical, and has a cristate system much more developed than in liver mitochondria. The matrix space is dearly visible. X 80,000 (Q A mitochondrion isolated from beef adrenal cortex and treated as in Also... 

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