Steroidhormonbiosynthese

Steroidhormone biosynthesis is the metabolic process by which steroid hormones are synthesized from cholesterol in the body. This process primarily occurs in the gonads, adrenal glands, and placenta. The initial step in steroidhormone biosynthesis is the conversion of cholesterol to pregnenolone by the enzyme cholesterol side-chain cleavage enzyme (P450scc). Pregnenolone is then converted to progesterone by the enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD). Progesterone is a precursor to several steroid hormones, including androgens, estrogens, and glucocorticoids. Androgens are synthesized from progesterone via the enzyme 17α-hydroxylase/C17,20-lyase (C17,20-lyase) and are further converted to testosterone by the enzyme 17β-hydroxysteroid dehydrogenase (17β-HSD). Estrogens are synthesized from progesterone via the enzyme aromatase, which converts androgens to estrogens. Glucocorticoids are synthesized from progesterone via the enzyme 21-hydroxylase, which converts progesterone to 11-deoxycortisol, and then to cortisol by the enzyme 11β-hydroxylase. The regulation of steroidhormone biosynthesis is complex and involves multiple feedback mechanisms to maintain homeostasis.