The participation of a second molecule of adrenodoxin in cytochrome P-450-catalyzed 11beta hydroxylation.
J Biol Chem, 1978/12/10;253(23):8355-8.
Seybert DW, Lambeth JD, Kamin H
PMID: 309471
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
Adrenal Glands; Adrenodoxin; Animals; Cattle; Cytochrome P-450 Enzyme System; Ferredoxin-NADP Reductase; Hydroxylation; Kinetics; Spectrophotometry; Steroid 11-beta-Hydroxylase; Steroid Hydroxylases
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