The enzymic conversion of cholesterol into pregnenolone involves a cleavage of the cholesterol. side-chain, yielding two fragments: pregnenolone and isocaproaldehyde (fig. 1.1). This process, the rate limiting step in the biosynthesis of the steroid hormones, is generally known as the "cholesterol side-chain cleavage" reaction. All the enzymes required for this conversion are located in the mitochondria of the adrenal cell, while the main regulating factor is the adrenocorticotropic hormone (ACTH) .

H.K.A. Visser (Henk)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam

Kraaipoel, R. J. (1978, January 20). Studies on cholesterol side-chain cleavage in adrenal cortex mitochondria : proposal of a new mechanism. Retrieved from