Uroporphyrinogens
Encyclopedia
Uroporphyrinogens are tetrapyrroles with four propionic acid
groups ("P" groups) and four acetic acid
groups ("A" groups).
There are four forms, which vary based upon the arrangements of the "P" and "A" groups (in clockwise order):
Propionic acid
Propanoic acid is a naturally occurring carboxylic acid with chemical formula CH3CH2COOH. It is a clear liquid with a pungent odor...
groups ("P" groups) and four acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
groups ("A" groups).
There are four forms, which vary based upon the arrangements of the "P" and "A" groups (in clockwise order):
- In the "I" variety (i.e. uroporphyrinogen IUroporphyrinogen IUroporphyrinogen I is a tetrapyrrole which accumulates in acute intermittent porphyria....
), the order repeats four times: AP-AP-AP-AP. - In the "III" variety (i.e. uroporphyrinogen IIIUroporphyrinogen IIIUroporphyrinogen III is an metabolic intermediate in the biosynthesis of protoporphyrin. It is created by the enzyme uroporphyrinogen III synthase, and is converted into coproporphyrinogen III by the enzyme uroporphyrinogen III decarboxylase.-See also:...
), the fourth is reversed: AP-AP-AP-PA.- This is the most common form. In the synthesis of porphyrinPorphyrinPorphyrins 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...
, it is created from hydroxymethyl bilane by the enzyme uroporphyrinogen III synthaseUroporphyrinogen III synthaseUroporphyrinogen III synthase is an enzyme involved in the metabolism of the cyclic tetrapyrrole compound porphyrin. It is involved in the conversion of hydroxymethyl bilane into uroporphyrinogen III...
, and it is converted into coproporphyrinogen IIICoproporphyrinogen IIIIn the metabolism of porphyrin, the enzyme uroporphyrinogen III decarboxylase generates coproporphyrinogen III from uroporphyrinogen III, and coproporphyrinogen III oxidase converts it into protoporphyrinogen IX....
by the enzyme uroporphyrinogen III decarboxylaseUroporphyrinogen III decarboxylaseUroporphyrinogen decarboxylase, also known as UROD, is an enzyme that in humans is encoded by the UROD gene.- Function :This gene encodes the fifth enzyme of the heme biosynthetic pathway...
.
- This is the most common form. In the synthesis of porphyrin
- The "II" and "IV" varieties can be created synthetically, but do not appear in nature.