steroid 21-monooxygenase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: A C(21) steroid + [reduced NADPH--hemoprotein reductase] + O2 = a 21-hydroxy-C(21)-steroid + [oxidized NADPH--hemoprotein reductase] + H2O. [RHEA:65612]

Steroid 21-monooxygenase activity refers to the enzymatic process that catalyzes the hydroxylation of steroids at the C21 position. This reaction is a crucial step in the biosynthesis of various steroid hormones, including cortisol, aldosterone, and progesterone. The enzyme responsible for this activity, known as CYP21A2, is a member of the cytochrome P450 superfamily.

The catalytic mechanism involves the binding of the steroid substrate to the active site of CYP21A2. The enzyme then utilizes molecular oxygen and NADPH as cofactors to introduce a hydroxyl group at the C21 position of the steroid molecule. This hydroxylation reaction results in the formation of a 21-hydroxysteroid intermediate, which is further processed by other enzymes in the steroid biosynthesis pathway.

The specific substrates of steroid 21-monooxygenase include various steroid precursors, such as pregnenolone, 17α-hydroxypregnenolone, progesterone, and 17α-hydroxyprogesterone. The enzyme exhibits high substrate specificity, ensuring that only the appropriate steroids are hydroxylated at the C21 position.

The deficiency of CYP21A2 activity can lead to various genetic disorders, including congenital adrenal hyperplasia (CAH). CAH is characterized by the accumulation of steroid precursors and the deficiency of cortisol production. This can result in various clinical manifestations, including salt-wasting, virilization, and hypertension.

Therefore, steroid 21-monooxygenase activity plays a vital role in the biosynthesis of essential steroid hormones, maintaining proper endocrine function, and preventing the development of genetic disorders like CAH.'
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Proteins (2)

Compounds (5)