Oxygen dependence of adrenal cortex cholesterol side chain cleavage. Implications in the rate-limiting steps in steroidogenesis.
The oxygen dependence of cholesterol side chain cleavage to form pregnenolone was
measured, using both purified phospholipid vesicle-reconstituted cytochrome P-450scc and
rat adrenal mitochondria. At saturating cholesterol and nonlimiting electron supply (via
NADPH-adrenodoxin reductase and adrenodoxin) the Km (O2) is low (4 microM).
Limitations in the availability of both cholesterol and reductant caused elevations in the
observed Km (O2). Pregnenolone synthesis was measured in mitochondria from variously …
measured, using both purified phospholipid vesicle-reconstituted cytochrome P-450scc and
rat adrenal mitochondria. At saturating cholesterol and nonlimiting electron supply (via
NADPH-adrenodoxin reductase and adrenodoxin) the Km (O2) is low (4 microM).
Limitations in the availability of both cholesterol and reductant caused elevations in the
observed Km (O2). Pregnenolone synthesis was measured in mitochondria from variously …
