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
  • InChI=1S/C36H44N4O8/c1-17-21(5-9-33(41)42)29-14-27-19(3)22(6-10-34(43)44)30(39-27)15-28-20(4)24(8-12-36(47)48)32(40-28)16-31-23(7-11-35(45)46)18(2)26(38-31)13-25(17)37-29/h37-40H,5-16H2,1-4H3,(H,41,42)(H,43,44)(H,45,46)(H,47,48) ☒N
  • InChI=1/C36H44N4O8/c1-17-21(5-9-33(41)42)29-14-27-19(3)22(6-10-34(43)44)30(39-27)15-28-20(4)24(8-12-36(47)48)32(40-28)16-31-23(7-11-35(45)46)18(2)26(38-31)13-25(17)37-29/h37-40H,5-16H2,1-4H3,(H,41,42)(H,43,44)(H,45,46)(H,47,48)
  • Cc1c2[nH]c(c1CCC(=O)O)Cc3c(c(c([nH]3)Cc4c(c(c([nH]4)Cc5c(c(c([nH]5)C2)C)CCC(=O)O)CCC(=O)O)C)CCC(=O)O)C
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).

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 −CH3 (M) and four propionic acid groups −CH2−CH2−COOH (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 −CH2−COOH into methyl groups −CH3, 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. ISBN 978-0470048672.
  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. S2CID 36820694.