Coproporphyrinogen III

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Coproporphyrinogen III
Coproporphyrinogen III.svg
IUPAC name
3-[8,12,17-tris(2-carboxyethyl)-3,7,13,18-tetramethyl-5,10,15,20,21,22, 23,24-octahydroporphyrin-2-yl]propanoic acid
3D model (JSmol)
MeSH Coproporphyrinogen+III
C36H44N4O8 protonated carboxylic acids
Molar mass 660.757 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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Infobox references

Coproporphyrinogen III is a metabolic intermediate in the biosynthesis of many compounds that are critical for living organisms, such as hemoglobin and chlorophyll. It is a colorless solid.

The compound is a porphyrinogen, a class of compounds characterized by a hexahydroporphine core with various side chains. The coproporphyrinogens have the outermost hydrogen atoms of the core replaced by four methyl groups –CH
(M) and four propionic acid groups –CH
(P). In coproporphyrogen III, the order around the outer ring is MP-MP-MP-PM. For comparison, coproporphyrinogen I has them in the sequence MP-MP-MP-MP. heme.

Biosynthesis and metabolism[edit]

In the main porphyrin biosynthesis pathway, coproporphyrinogen III is derived from uroporphyrinogen III by the action of the enzyme uroporphyrinogen III decarboxylase:

Biosynthesis of coproporphyrinogen-III from uroporphyrinogen-III

The conversion entails four decarboxylations, which turn the four acetic acid groups –CH
into methyl groups –CH
, with release of four carbon dioxide molecules.[1][2]

Coproporphyrinogen III is further used as a substrate for the enzyme coproporphyrinogen III oxidase which oxidizes and further decarboxylates it to protoporphyrinogen IX.


  1. ^ Paul R. Ortiz de Montellano (2008). "Hemes in Biology". Wiley Encyclopedia of Chemical Biology. John Wiley & Sons. doi:10.1002/9780470048672.wecb221.
  2. ^ Sassa, S.; Kappas, A. (2000). "Molecular aspects of the inherited porphyrias". Journal of Internal Medicine. 247 (2): 169–78. doi:10.1046/j.1365-2796.2000.00618.x. PMID 10692079.