Porphobilinogen synthase (d-aminolevulinic acid dehydratase):
Is the control step in heme synthesis
- Is inhibited by lead
Requires pyridoxal (B6) phosphate for activity
- Is present in the cytosol
A, B and C
A and C
- B and D
All of the above
- The key control enzyme is ALA synthase.
- This enzyme is very sensitive to lead. When it is inhibited its substrate, d-aminolevulinic acid, accumulates.
- ALA synthase requires vitamin B6, not this enzyme.
- This is the first of the cytoplasmic enzymes of heme synthesis.
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