title: The participation of a second molecule of adrenodoxin in cytochrome P-450-catalyzed 11beta hydroxylation.
abstract: We have utilized 11beta-hydroxylase activity and visible absorption spectrophotometry to detect possible complex formation among adrenodoxin reductase, adrenodoxin, and cytochrome P-450(11)beta. At low ionic strength, a 1:1 complex between adrenodoxin reductase and adrenodoxin occurs but does not support maximal rates of 11beta hydroxylation; at least 1 additional molecule of adrenodoxin in excess of the 1:1 complex is required for full hydroxylase activity. Spectrophotometric titration of a mixture of adrenodoxin reductase and cytochrome P-450(11)beta with adrenodoxin indicates sequential formation of 1:1 complexes between adrenodoxin reductase and adrenodoxin and then between a second adrenodoxin and cytochrome P-450(11beta; the adrenodoxin-cytochrome P-450(11)beta complex is only detectable when the concentration of adrenodoxin exceeds that of adrenodoxin reductase.
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism*; D000325:Adrenodoxin / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism; D006900:Hydroxylation; D007700:Kinetics; D013053:Spectrophotometry; D013252:Steroid 11-beta-Hydroxylase / Q000378:metabolism*; D013250:Steroid Hydroxylases / Q000378:metabolism*
chemical_list: D000325:Adrenodoxin; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D013252:Steroid 11-beta-Hydroxylase; D005287:Ferredoxin-NADP Reductase