Hydroxymethylbilane
Intermediate in the synthesis of porphyrins
From Wikipedia, the free encyclopedia
Hydroxymethylbilane, also known as preuroporphyrinogen, is an organic compound that occurs in living organisms during the synthesis of porphyrins, a group of critical substances that include haemoglobin, myoglobin, and chlorophyll. The name is often abbreviated as HMB.
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| Names | |
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| IUPAC name
3,3′,3′′,3′′′-[3,8,13,18-Tetrakis(carboxymethyl)-19-(hydroxymethyl)-5,10,15,22,23,24-hexahydro-21H-biline-2,7,12,17-tetrayl]tetrapropanoic acid | |
| Systematic IUPAC name
3,3′,3′′,3′′′-[14,33,53,73-Tetrakis(carboxymethyl)-15-(hydroxymethyl)-11H,31H,51H,71H-1,7(2),3,5(2,5)-tetrapyrrolaheptaphane-13,34,54,74-tetrayl]tetrapropanoic acid | |
| Identifiers | |
3D model (JSmol) |
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| 1209089 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| KEGG | |
| MeSH | hydroxymethylbilane |
PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| C40H46N4O17 | |
| Molar mass | 854.81 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure
The compound is a substituted bilane, a chain of four pyrrole rings interconnected by methylene bridges −CH2−. The chain starts with a hydroxymethyl group −CH2−OH and ends with a hydrogen, in place of the respective methylene bridges. The other two carbon atoms of each pyrrole cycle are connected to an acetic acid group −CH2−COOH and a propionic acid group −CH2−CH2−COOH, in that order.[1]
Metabolism
HMB is generated from four molecules of porphobilinogen by the enzyme porphobilinogen deaminase in the overall reaction:[2][3]
The enzyme uroporphyrinogen III synthase catalyses the cyclisation reaction of hydroxymethylbilane into uroporphyrinogen III via a spiro intermediate which allows one of the pyrrole rings to convert its initial acetate to propionate configuration into a propionate-acetate one.[2][4][5]
Uroporphyrinogen III is a porphyrinogen, which is a class of compounds with the hexahydroporphine macrocycle. In the absence of the enzyme, the compound undergoes spontaneous cyclization and becomes uroporphyrinogen I.[6][7]