Immunochemical and functional similarities and differences among iron-sulfur proteins involved in mammalian steroidogenesis.

An antibody prepared against bovine adrenodoxin has been employed to study possible similarities or differences among the iron-sulfur protein components of electron transport sequences associated with cytochrome P-450 function in the mitochondria of mammalian steroidogenic tissues. Although they are not identical, the "adrenodoxins" in mitochondria from the adrenals of a number of species, including man, are both immunochemically and functionally similar. The ability of the antibody to inhibit adrenal 11 beta-hydroxylase and cholesterol side-chain cleavage activities demonstrates the requirement for adrenodoxin in these mixed-function oxidations. The results presented also demonstrate the immunochemical and functional similarities among the iron-sulfur proteins which are involved in the oxidative cleavage of the cholesterol side-chain occurring in adrenal, ovarian and testicular mitochondria. The iron-sulfur protein involved in cholesterol side-chain cleavage activity in term placental mitochondria, however, appears to be immunochemically different from these other proteins.