Bovine adrenodoxin

Fig. 21. The primary structure of bovine adrenodoxin (272). Potential iron-binding cysteinyls are found in positions 46. 52, 55, 92, 95 ...

Fig. 26. The polypeptide backbone absorption region optical activity of two 2Fe 2S proteins (299). The ultraviolet ORD (A) and CD (B) spectra of bovine adrenodoxin (—) and spinach ferredoxin (—), taken in aqueous solutions, pH 7.4...

Chen, J. Y., and Waterman, M. R. (1992). Two promoters in the bovine adrenodoxin gene and the role of associated, unique cAMP-responsive sequences. Biochemistry 31, 2400-2407. 

R. Bernhardt, and U. Heinemann (1998). New aspects of electron transfer revealed by the crystal structure of a truncated bovine adrenodoxin, Adx(4-108). Structure 6, 269-280. 

Pikuleva, I.A., K. Tesh, M.R. Waterman, and Y. Kim (2000). The tertiary structure of full-length bovine adrenodoxin suggests functional dimers. Arch. Biochem. Biophys. 373, 44-55. 

Uhlmann, Ff., V Beckert, D. Schwarz, and R. Bernhardt (1992). Expression of bovine adrenodoxin in E. coli and site-directed mutagenesis of /2 Fe-2S/ cluster ligands. Biochem. Biophys. Res. Commun. 188, 1131-1138. 

FeS cluster displacement experiments on Cp2 in 80% hexamethylphos-phoramide, Tris buffer + thiophenol yielded spectra very similar to those obtained by extruding clusters from C. pasteurianum ferredoxin (4Fe4S clusters) and quite dissimilar to that with bovine adrenodoxin which contains a 2Fe2S cluster (Orme-Johnson et ai, 1977). 

Also, the hydroxylation of several 3-keto-4-ene steroids by bacterial CYP106A2 from B. megaterium ATCC 13368 was carried out when supported by a cofactor regeneration enzyme. CYP106A2 was the first bacterial P450 found to catalyze the oxidation of steroids [100, 101]. Interestingly, bovine adrenodoxin (Adx) and adrenodoxin reductase (AdR) have successfully been implemented for efficient... 

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). 

Usanov SA, Graham SE, Lepesheva GI, et al. Probing the interaction of bovine cytochrome P450scc (CYP11A1) with adrenodoxin evaluating site-directed mutations by molecular modeling. Biochemistry 2002 41 8310-8320. 

In 2011, Pikuleva s group [1952] reported a stmcture of bovine P450 llAl bound to 22-hy-droxycholesterol, the first reaction product (from cholesterol). The active site cavity can be described as a long curved tube that extends from the surface to the heme group. (A linker was used to tether adrenodoxin to P450 llAl.) The [2Fe-2S] iron clnster of adrenodoxin was positioned 17 A away from the heme iron of P450 llAl. 

Studies with bovine P450 llAl indicated the significance of Lys-377 and Lys-381 in adrenodoxin binding [1955], As indicated earlier, a mutation at Arg-353 was found to attenuate the function of P450 llAl in a patient [1925]. Site-directed mntagenesis of human P450 llAl (in E. coli) indicated that Ile-462 had some effect on kinetic parameters [1956]. 

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