Reaction:
(1) testosterone + 3 O2 + 3 [reduced NADPH—hemoprotein reductase] = 17β-estradiol + formate + 4 H2O + 3 [oxidized NADPH—hemoprotein reductase] (overall reaction)
(1a) testosterone + O2 + [reduced NADPH—hemoprotein reductase] = 19-hydroxytestosterone + H2O + [oxidized NADPH—hemoprotein reductase]
(1b) 19-hydroxytestosterone + O2 + [reduced NADPH—hemoprotein reductase] = 19-oxotestosterone + 2 H2O + [oxidized NADPH—hemoprotein reductase]
(1c) 19-oxotestosterone + O2 + [reduced NADPH—hemoprotein reductase] = 17β-estradiol + formate + H2O + [oxidized NADPH—hemoprotein reductase]
(2) androst-4-ene-3,17-dione + 3 O2 + 3 [reduced NADPH—hemoprotein reductase] = estrone + formate + 4 H2O + 3 [oxidized NADPH—hemoprotein reductase] (overall reaction)
(2a) androst-4-ene-3,17-dione + O2 + [reduced NADPH—hemoprotein reductase] = 19-hydroxyandrost-4-ene-3,17-dione + H2O + [oxidized NADPH—hemoprotein reductase]
(2b) 19-hydroxyandrost-4-ene-3,17-dione + O2 + [reduced NADPH—hemoprotein reductase] = 19-oxo-androst-4-ene-3,17-dione + 2 H2O + [oxidized NADPH—hemoprotein reductase]
(2c) 19-oxoandrost-4-ene-3,17-dione + O2 + [reduced NADPH—hemoprotein reductase] = estrone + formate + H2O + [oxidized NADPH—hemoprotein reductase]
Other name(s): CYP19A1 (gene name); estrogen synthetase (incorrect)
Systematic name: testosterone monooxygenase (17β-estradiol-forming)
Comments: A cytochrome P450. The enzyme catalyses three sequential hydroxylations of the androgens androst-4-ene-3,17-dione and testosterone, resulting in their aromatization and forming the estrogens estrone and 17β-estradiol, respectively.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:
References:
1. Thompson, E.A., Jr. and Siiteri, P.K. The involvement of human placental microsomal cytochrome P-450 in aromatization. J. Biol. Chem. 249 (1974) 5373-5378. [PMID: 4370479]
2. Fishman, J. and Goto, J. Mechanism of estrogen biosynthesis. Participation of multiple enzyme sites in placental aromatase hydroxylations. J. Biol. Chem. 256 (1981) 4466-4471. [PMID: 7217091]
3. Kellis, J.T., Jr. and Vickery, L.E. Purification and characterization of human placental aromatase cytochrome P-450. J. Biol. Chem. 262 (1987) 4413-4420. [PMID: 3104339]
4. Ghosh, D., Griswold, J., Erman, M. and Pangborn, W. Structural basis for androgen specificity and oestrogen synthesis in human aromatase. Nature 457 (2009) 219-223. [PMID: 19129847]