Question 13 of 13
The answer you chose is highlighted in reverse video. The correct answer is in bold.
Delta-aminolevulinic acid synthase:
- 1. requires pyridoxal phosphate for activity.
- 2. synthesis can be induced by phenobarbital and some
steroids.
- 3. is inhibited by heme.
- 4. is inhibited by lead.
- A. 1, 2 and 3
- B. 1 and 3
- C. 2 and 4
- D. 4 only
- E. All of the above
The correct answer is (A).
Comments:
- 1. Pyridoxal (vitamin B6) phosphate antagonists, such as the anti-tuberculosis drug, isoniazide, can inhibit this enzyme.
- 2. Phenobarbital is contraindicated for patients with porphyria for this reason.
- 3. This is a major physiological control.
- 4. ALA dehydratase and ferrochelatase are notably lead-sensitive.
Return to Question Document
Return to Main Menu
jb
Last modified 1/5/95