Porphyrin Biosynthesis (early stages)

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© IUBMB 2003

For nomenclature of tetrapyrroles, click here.

In the reaction of EC, the substrate forms an imine with the amino group of a lysine residue of the enzyme.

In the absence of EC, which cyclizes hydroxymethylbilane with reversal of ring D, cyclization occurs spontaneously, without such reversal, forming uroporphyrinogen I.

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porphyrin biosynthesis (later stages)
corrin biosynthesis
EC glutamate-tRNA reductase
EC 5-aminolevulinate synthase
EC hydroxymethylbilane synthase
EC porphobilinogen synthase
EC uroporphyrinogen-III synthase (mechanism)
EC glutamate-1-semialdehyde 2,1-aminomutase(mechanism)
EC glutamate—tRNA ligase