Uroporphyrinogen III synthase () is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
involved in the
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
of the cyclic
tetrapyrrole
Tetrapyrroles are a class of chemical compounds that contain four pyrrole or pyrrole-like rings. The pyrrole/pyrrole derivatives are linked by ( =- or -- units), in either a linear or a cyclic fashion. Pyrroles are a five-atom ring with four car ...
compound
porphyrin
Porphyrins ( ) are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−). The parent of porphyrin is porphine, a rare chemical com ...
. It is involved in the conversion of
hydroxymethyl bilane into
uroporphyrinogen III
Uroporphyrinogen III is a tetrapyrrole, the first macrocyclic intermediate in the biosynthesis of heme, chlorophyll, vitamin B12, and siroheme. It is a colorless compound, like other porphyrinogens.
Structure
The molecular structure of uroporphy ...
. This enzyme
catalyses the inversion of the final
pyrrole unit (ring D) of the linear tetrapyrrole molecule, linking it to the first pyrrole unit (ring A), thereby generating a large macrocyclic structure, uroporphyrinogen III.
The enzyme
folds into two alpha/beta
domains connected by a beta-ladder, the
active site being located between the two
domains.
Pathology
A deficiency is associated with
Gunther's disease, also known as congenital erythropoietic porphyria (CEP). This is an
autosomal recessive inborn error of metabolism that results from the markedly deficient activity of uroporphyrinogen III synthase.
References
External links
*
EC 4.2.1
{{lyase-stub