Enzymes

Question 1

5-alpha reductase

Answer 1

converts testosterone –> DHT (dihydrotestosterone)
- DHT is active form of androgen for all functions except fetal testes production (only internal genetalia) and negative feedback to pituitary for gonadotropin secretion

Question 2

5’-deiodinase enzyme

Answer 2

activates T4 to T3

- inhibited by PTU

Question 3

20,22-desmolase

Answer 3

converts cholesterol into pregnenolone (in mitochondria)

• rate limiting step of adrenal steroid biosynthesis
• facilitated by adrenocorticotropin (ACTH)

Question 4

3-hydroxysteroid dehydrogenase

Answer 4

converts pregnenolone to progesterone

-

Question 5

aldose reductase

Answer 5

converts excess glucose –> sorbitol

- sorbitol accumulates w/in cell, draws water –> osmotic injury (e.g., cataracts, peripheral neuropathy in DMT2)