Cholesterol side-chain cleavage enzyme is commonly referred to as P450scc, where "scc" is an acronym for side-chain cleavage. P450scc is a mitochondrial enzyme that catalyzes conversion of cholesterol to pregnenolone. This is the first reaction in the process of steroidogenesis in all mammalian tissues that specialize in the production of various steroid hormones.
2). This critical step, which is subject to hormonal control by the adrenocorticotropic hormone (ACTH) in the adrenals and by the luteinizing hormone (LH) in the gonads, is catalysed by a P-450 enzyme, the cholesterol side-chain cleavage enzyme P-450scc (also called 20,22-desmolase, or 20,22-lyase). Pregnenolone can be converted either to progesterone, which branches to the glucocorticoid and androgen/estrogen pathways, or to 17α-hydroxypregnenolone, which is another route for the formation of androgens and estrogens (Fig.