Hydroxymethylbilane
Encyclopedia
Hydroxymethylbilane also known as preuroporphyrinogen, is a molecule involved in the metabolism of porphyrin
. In the third step, it is generated by the enzyme porphobilinogen deaminase
, and in the next step the enzyme uroporphyrinogen III synthase
converts it into uroporphyrinogen III
.
In general, defects of heme
synthesis after formation of HMB lead to photosensitivity
.
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...
. In the third step, it is generated 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...
, and in the next step the enzyme uroporphyrinogen III synthase
Uroporphyrinogen III synthase
Uroporphyrinogen 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...
converts it into uroporphyrinogen III
Uroporphyrinogen III
Uroporphyrinogen 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:...
.
In general, defects of heme
Heme
A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...
synthesis after formation of HMB lead to photosensitivity
Photosensitivity
Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.- Human medicine :Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn...
.