Cross-linking studies of adrenocortical cytochrome P-450scc. Evidence for a covalent complex with adrenodoxin and localization of the adrenodoxin-binding domain.

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TitleCross-linking studies of adrenocortical cytochrome P-450scc. Evidence for a covalent complex with adrenodoxin and localization of the adrenodoxin-binding domain.
Publication TypeJournal Article
Year of Publication1985
AuthorsChashchin, VL, Turko, IV, Akhrem, AA, Usanov, SA
JournalBiochim Biophys Acta
Volume828
Issue3
Pagination313-24
Date Published1985 Apr 29
ISSN0006-3002
KeywordsAdrenal Cortex, Adrenodoxin, Animals, Binding Sites, Cholesterol Side-Chain Cleavage Enzyme, Cross-Linking Reagents, Cytochrome P-450 Enzyme System, Electron Transport, Imidoesters, Molecular Weight, Oxidoreductases, Rabbits
Abstract

A cleavable cross-linking reagent, dimethyl-3,3'-dithiobispropionimidate, was used to study the molecular organization of adrenocortical cytochrome P-450scc. Extensive cross-linking was found to occur, resulting in the formation of heterologous oligomers up to octamer. The covalently cross-linked complex of adrenocortical cytochrome P-450scc with adrenodoxin has been obtained by using dimethyl-3,3'-dithiobispropionimidate. In the presence of NADPH and adrenodoxin reductase, electron transfer to cytochrome P-450scc occurs in the complex, and, in the presence of cholesterol, the latter effectively oxidizes to pregnenolone. By using covalently immobilized adrenodoxin and heterobifunctional reagent, N-succinimidyl-3-(2-pyridyldithio)propionate, the adrenodoxin-binding site was shown to be located in the heme-containing, catalytic domain of cytochrome P-450scc. The data obtained indicate the existence of two different sites on the adrenodoxin molecule that are responsible for the interaction with adrenodoxin reductase and cytochrome P-450scc. This is consistent with the model mechanism of electron transfer in the organized complex.

Alternate JournalBiochim. Biophys. Acta
PubMed ID3838683