In heme synthesis in mammalian cells:

  1. Succinyl CoA and alanine are the immediate substrates for formation of d-aminolevulinic acid
  2. Ferric iron is inserted into protoporphyrin IX
  3. Coproporphyrin IV is an intermediate
  4. Porphobilinogen is formed by the condensation of two molecules of d-aminolevulinic acid


  1. The amino acid is glycine, not alanine
  2. Ferrous iron, or iron (II), is inserted to make heme
  3. Only the I and III series of porphyrins occur naturally
  4. Correct, and the name of the enzyme is ALA dehydratase

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