The constitutive 7-ethoxycoumarin O-deethylase activity of human placental microsomes: Relationship to aromatase
| Autor: | Robert A. Meigs |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
medicine.medical_specialty
medicine.drug_class Placenta Biophysics 7-Alkoxycoumarin O-Dealkylase Biochemistry Aromatase Pregnancy Microsomes Internal medicine medicine Humans Molecular Biology Estrogen synthesis 7-ethoxycoumarin Oxidase test biology Aromatization Cell Biology Androgen Kinetics Endocrinology Androgens Oxygenases Microsome biology.protein Female |
| Zdroj: | Biochemical and Biophysical Research Communications. 145:1012-1018 |
| ISSN: | 0006-291X |
| DOI: | 10.1016/0006-291x(87)91536-1 |
| Popis: | The constitutive 7-ethoxycoumarin deethylase activity of human placental microsomes from non-smokers was acutely inhibited by a number of androgens which serve as substrates for and/or competitive inhibitors of estrogen synthesis by the aromatase activity of these preparations. 10β-(2-Propynyl)estr-4-ene-3,17-dione and 4-hydroxyandrost-4-ene-3,17-dione, androgen derivatives which produce a mechanism-based, time-dependent inactivation of placental aromatase caused a cofactor-dependent decay in deethylase activity which paralleled the loss of aromatase activity caused by these agents and which was antagonized by aromatase substrates. Conversely, 7-ethyoxycoumarin antagonized the time-dependent action of 10β-(2-propynyl)estr-4-ene-3,17-dione and 4-hydroxyandrost-4-ene-3,17-dione on aromatase and inhibited competitively the aromatization of 4-androstene-3,17-dione. The Ki for 7-ethoxycoumarin was equivalent to its Km as substrate for deethylation. It is concluded that a common oxidase species is responsible for both the aromatase and constitutive 7-ethoxycoumarin deethylase activities of human placental microsomes. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|