Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen into the other donor

testosteronel,NADPH---hemoprotein reductase:oxygen oxidoreductase (17beta-estradiol-forming)

(1) testosterone + 3 O2 + 3 [reduced NADPH---hemoprotein reductase] = 17beta-estradiol + formate + 4 H2O + 3 [oxidized NADPH---hemoprotein reductase] (overall reaction) [RN:R10511];
(1a) testosterone + O2 + [reduced NADPH---hemoprotein reductase] = 19-hydroxytestosterone + H2O + [oxidized NADPH---hemoprotein reductase] [RN:R02501];
(1b) 19-hydroxytestosterone + O2 + [reduced NADPH---hemoprotein reductase] = 19-oxotestosterone + 2 H2O + [oxidized NADPH---hemoprotein reductase] [RN:R04761];
(1c) 19-oxotestosterone + O2 + [reduced NADPH---hemoprotein reductase] = 17beta-estradiol + formate + H2O + [oxidized NADPH---hemoprotein reductase] [RN:R03087];
(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) [RN:R10515];
(2a) androst-4-ene-3,17-dione + O2 + [reduced NADPH---hemoprotein reductase] = 19-hydroxyandrost-4-ene-3,17-dione + H2O + [oxidized NADPH---hemoprotein reductase] [RN:R01840];
(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] [RN:R04759];
(2c) 19-oxoandrost-4-ene-3,17-dione + O2 + [reduced NADPH---hemoprotein reductase] = estrone + formate + H2O + [oxidized NADPH---hemoprotein reductase] [RN:R02351]

R01840 R02351 R02501 R03087 R04759 R04761 R10511 R10515

testosterone [CPD:C00535];
O2 [CPD:C00007];
[reduced NADPH---hemoprotein reductase] [CPD:C03024];
19-hydroxytestosterone [CPD:C05294];
19-oxotestosterone [CPD:C05295];
androst-4-ene-3,17-dione [CPD:C00280];
19-hydroxyandrost-4-ene-3,17-dione [CPD:C05290];
19-oxoandrost-4-ene-3,17-dione [CPD:C05297]

A cytochrome P-450. 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 17beta-estradiol, respectively. The direct electron donor to the enzyme is EC 1.6.2.4, NADPH---hemoprotein reductase.

EC 1.14.14.14 created 2013

1  [PMID:4370479]

Thompson EA Jr, Siiteri PK

The involvement of human placental microsomal cytochrome P-450 in aromatization.

J Biol Chem 249:5373-8 (1974)

2  [PMID:7217091]

Fishman J, Goto J

Mechanism of estrogen biosynthesis. Participation of multiple enzyme sites in placental aromatase hydroxylations.

J Biol Chem 256:4466-71 (1981)

3  [PMID:3104339]

Kellis JT Jr, Vickery LE

Purification and characterization of human placental aromatase cytochrome P-450.

J Biol Chem 262:4413-20 (1987)

4  [PMID:19129847]

Ghosh D, Griswold J, Erman M, Pangborn W

Structural basis for androgen specificity and oestrogen synthesis in human aromatase.

Nature 457:219-23 (2009)
DOI:10.1038/nature07614

[hsa:1588]