Multiple choice

What is true about aminolevulinic acid synthase?

  1. It requires NAD for its activity.

  2. It is allosterically activated by heme.

  3. Its synthesis is inhibited by steroids.

  4. Its synthesis can be induced by drugs.

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Aminolevulinic acid (ALA) synthase is the rate-limiting enzyme in heme synthesis, and its transcription can be induced by certain drugs (like barbiturates) through cytochrome P450 induction. It requires pyridoxal phosphate (not NAD), is inhibited by heme (feedback inhibition), and steroids don't directly inhibit its synthesis.