Porphobilinogen
Porphobilinogen is an organic compound that occurs in living organisms as an intermediate in the biosynthesis of porphyrins, which include critical substances like hemoglobin and chlorophyll. The name is often abbreviated PBG.
The structure of the molecule can be described as molecule of pyrrole with sidechains substituted for hydrogen atoms at positions 2, 3 and 4 in the ring ; respectively, an aminomethyl group, an acetic acid group, and a propionic acid group.Biosynthesis
In the first step of the porphyrin biosynthesis pathway, porphobilinogen is generated from aminolevulinate by the enzyme ALA dehydratase.
Metabolism
In the typical porphyrin biosynthesis pathway, four molecules of porphobilinogen are concatenated by carbons 2 and 5 of the pyrrole ring into hydroxymethyl bilane by the enzyme porphobilinogen deaminase, also known as hydroxymethylbilane synthase.Pathologies
causes an increase in urinary porphobilinogen.
