Question

Which of the following enzymes is responsible for conversion of testosterone to 17\(\beta\)-estradiol?

• A. 3\(\beta\)-Hydroxysteroid dehydrogenase
• B. 17\(\beta\)-Hydroxysteroid dehydrogenase
• C. Aromatase
• D. 5\(\alpha\)-reductase

Hint:

Steroid Enzymology:
Aromatase (CYP19A1) $\rightarrow$ Testosterone to 17$\beta$-Estradiol.
5$\alpha$-Reductase $\rightarrow$ Testosterone to Dihydrotestosterone (DHT).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Steroidogenesis involves cytochrome P450 monooxygenases that catalyze the aromatization of neutral androgen C19 sterols into phenolic C18 estrogens.
Key Formula or Approach:
\[ \text{Testosterone (C19)} + 3\text{O}_2 + 3\text{NADPH} \xrightarrow{\text{Aromatase (CYP19A1)}} 17\beta\text{-Estradiol (C18)} + \text{Formate} + 3\text{H}_2\text{O} + 3\text{NADP}^+ \]

Step 2: Detailed Explanation:
Aromatase (Estrogen Synthase CYP19A1) is the terminal enzyme complex in estrogen biosynthesis:
- It catalyzes three consecutive hydroxylation reactions removing the C-19 angular methyl group and converting the neutral cyclohexenone A-ring of androgens into the aromatic phenolic A-ring of estrogens.
- Specifically converts Testosterone to 17$\beta$-Estradiol and androstenedione to estrone.

Step 3: Final Answer:
Hence, Aromatase is responsible for this conversion, matching option (C).