Porphobilinogen
Encyclopedia
Porphobilinogen is a pyrrole
involved in porphyrin
metabolism.
It is generated by aminolevulinate (ALA) and the enzyme
ALA dehydratase. PBG is then converted into hydroxymethyl bilane by the enzyme porphobilinogen deaminase
, also known as hydroxymethylbilane synthase.
Acute intermittent porphyria
causes an increase in urinary porphobilinogen.
Pyrrole
Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H4NH. It is a colourless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3...
involved in porphyrin
Porphyrin
Porphyrins are a group of organic compounds, many naturally occurring. One of the best-known porphyrins is heme, the pigment in red blood cells; heme is a cofactor of the protein hemoglobin. Porphyrins are heterocyclic macrocycles composed of four modified pyrrole subunits interconnected at...
metabolism.
It is generated by aminolevulinate (ALA) and the enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
ALA dehydratase. PBG is then converted into hydroxymethyl bilane by the enzyme porphobilinogen deaminase
Porphobilinogen deaminase
Porphobilinogen deaminase is an enzyme involved in the third step of the metabolism of porphyrin, converting porphobilinogen into hydroxymethylbilane. The enzyme has the unique cofactor dipyrromethane...
, also known as hydroxymethylbilane synthase.
Acute intermittent porphyria
Acute intermittent porphyria
Acute intermittent porphyria is a rare autosomal dominant metabolic disorder affecting the production of heme, the oxygen-binding prosthetic group of hemoglobin. It is characterized by a deficiency of the enzyme porphobilinogen deaminase. Acute intermittent porphyria is the second most common...
causes an increase in urinary porphobilinogen.