What is the Origin of CYP11A1 Activity?

The term is derived from the standardized nomenclature for Cytochrome P450 enzymes in biochemistry and molecular biology. "CYP" denotes the Cytochrome P450 superfamily of monooxygenases, "11" indicates the gene family, "A" the subfamily, and "1" the specific gene. The designation CYP11A1 reflects its chemical function of cleaving the side chain of cholesterol at the 20 and 22 positions. Its clinical relevance stems from congenital adrenal hyperplasia disorders linked to its dysfunction.

What is the Mechanism of CYP11A1 Activity?

The mechanism of CYP11A1 activity takes place within the inner mitochondrial membrane of steroidogenic cells in the adrenal glands, gonads, and placenta. Cholesterol is first transported to the inner membrane, a process often mediated by StAR protein. CYP11A1 then performs three sequential hydroxylation reactions, requiring molecular oxygen and NADPH, to cleave the C20-C22 bond of the cholesterol side chain. This cleavage produces pregnenolone, the foundational precursor for all subsequent steroid hormone classes.

CYP11A1 Activity ∞ Area

CYP11A1 Activity

Meaning

CYP11A1 Activity refers to the enzymatic function of Cholesterol Side-Chain Cleavage Enzyme, also known as P450scc, a critical enzyme initiating the synthesis of all steroid hormones. This enzyme, encoded by the CYP11A1 gene, catalyzes the first committed and rate-limiting step in steroidogenesis: the conversion of cholesterol into pregnenolone. The level of this activity directly dictates the overall flux of the steroidogenesis pathway, influencing the production of cortisol, aldosterone, and sex steroids. Optimal CYP11A1 function is essential for maintaining the entire endocrine cascade and metabolic homeostasis.