[Interaction between cytochrome P-450scc and adrenodoxin in solution under effects of low spin effectors]

The interaction between cytochrome P-450scc and adrenodoxin and cholesterol under effects of low spin effectors (detergents, pregnolone) was studied. The increase in Tween 20 concentration causes a rise in the Kd values for cytochrome P-450scc complexes with adrenodoxin and cholesterol. Both cholesterol and adrenodoxin can convert the low spin form of cytochrome P-450scc obtained by addition of Tween 20 to the high spin form; however, their combined action results in higher values of the spin state index (A393/A418) at final titration points. The low spin form of the cytochrome induced by pregnolone as well as the low spin forms obtained by addition of detergents and the increase of pH and temperature are produced without cholesterol removal from the hemoprotein active center. An addition of adrenodoxin to these forms generates a spectral transition which is typical for the high spin form production.