Heme synthesis occurs in the bone marrow and liver. Deficiency of δ-aminolevulinic acid hydrase would lead to the accumulation of which of the following
1.δ-Aminolevulinic acid
2.Coproporphyrinogen
3.Glycine
4.Porphobilinogen
5.Succinyl-CoA
Solution:
δ-Aminolevulinic acid (δ-ALA) synthase irreversibly catalyzes the first reaction, glycine + succinyl-CoA → δ-ALA. This is the rate-limiting and committed step in heme synthesis. δ-ALA dehydratase catalyzes the second step in heme synthesis, 2δ-ALA → porphobilinogen. Since δ-aminolevulinic synthetases action is irreversible, only δ-ALA would accumulate.