Last modified: Fri Jul 9 14:34:24 BST 2004

Steroid carbon nomenclature

Trivial names: Progesterone; Progestin
Systematic name: Pregn-4-ene-3,20-dione
Molecular formula: C21H30O2
CAS Number: 57-83-0
Merck Index (11th Ed) Number: 7783


Pathway: Progesterone -> 6ß-Hydroxyprogesterone
Reaction: steroid ß-hydroxylation at C6
Enzyme: steroid 6ß-hydroxylase (steroid 6ß-hydroxylase), CYP3A [1]
EC Enzyme: P450 3b, CYP2C3 [2]
EC Enzyme: P450HP, CYP4B1 [3]


Pathway: Progesterone -> 11ß-Hydroxyprogesterone
Reaction: steroid ß-hydroxylation at C11
Enzyme: P450c11 (steroid 11ß-hydroxylase), CYP11B [4]
EC Enzyme: Cochliobolus lunatus P450C.l. (progesterone 11ß-hydroxylase) [5]

Substrate [5]

Progesterone -> 14alpha-Dihydroxyprogesterone
Reaction: steroid alpha-hydroxylation at C14
Enzyme: Cochliobolus lunatus P450C.l. (progesterone 14alpha-hydroxylase)


Pathway: Progesterone -> 16alpha-Hydroxyprogesterone
Reaction: steroid alpha-hydroxylation at C16
Enzyme: steroid 16alpha-hydroxylase, CYP3A [3]
EC Enzyme: P450NMb, CYP2G1 [6]

Substrate [4]

Pathway: Progesterone -> 17alpha-Hydroxyprogesterone
Reaction: steroid alpha-hydroxylation at C17
Enzyme: P450c17 (steroid 17alpha-hydroxylase/17,20-lyase), CYP17


Pathway: Progesterone -> 11-Deoxycorticosterone
Reaction: steroid hydroxylation at C21
Enzyme: P450c21 (steroid 21-hydroxylase), CYP21A [4]
EC Enzyme: progesterone 21-hydroxylase, CYP2C [7]
EC Enzyme: progesterone 21-hydroxylase, CYP2B11 [8]


  1. Chang, T.K., Teixeira, J., Gil, G. and Waxman, D.J. (1993) The lithocholic acid 6ß-hydroxylase cytochrome P-450, CYP 3A10, is an active catalyst of steroid-hormone 6ß-hydroxylation. Biochem. J. 291, 429-433.
  2. Richardson, T.H. and Johnson, E.F. (1994) Alterations of the regiospecificity of progesterone metabolism by the mutagenesis of two key amino acid residues in rabbit cytochrome P450 2C3v. J. Biol. Chem. 269, 23937-23943.
  3. Waxman, D.J., Lapenson, D.P., Aoyama, T., Gelboin, H.V., Gonzalez, F.J. and Korzekwa, K. (1991) Steroid hormone hydroxylase specificities of eleven cDNA-expressed human cytochrome P450s. Arch. Biochem. Biophys. 290, 160-166.
  4. Ruckpaul, K. and Rein, H., Eds. (1990) Frontiers in Biotransformation, vol. 3: Molecular Mechanisms of Adrenal Steroidogenesis and Aspects of Regulation and Application. Taylor & Francis, London.
  5. Vitas, M., Rozman, D., Komel, R. and Kelly, S.L. (1995) P450 mediated progesterone hydroxylation in Cochliobolus lunatus. J. Biotechnol. 42, 145-150.
  6. Ding, X. and Coon, M.J. (1994) Steroid metabolism by rabbit olfactory-specific P450 2G1. Arch. Biochem. Biophys. 315, 454-459.
  7. Richardson, T.H., Jung, F., Griffin, K.J., Wester, M., Raucy, J.L., Kemper, B., Bornheim, L.M., Hassett, C., Omiecinski, C.J. and Johnson, E.F. (1995) A universal approach to the expression of human and rabbit cytochrome P450s of the 2C subfamily in Escherichia coli. Arch. Biochem. Biophys. 323, 87-96.
  8. Born, S.L., John, G.H., Harlow, G.R. and Halpert, J.R. (1995) Characterization of the progesterone 21-hydroxylase activity of canine cytochrome P450 PBD-2/P450 2B11 through reconstitution, heterologous expression, and site-directed mutagenesis. Drug Metab. Dispos. 23, 702-707.

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