Coproporphyrinogen I

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Coproporphyrinogen I
Coproporphyrinogen I.svg
IUPAC name
3-[7,12,17-tris(2-carboxyethyl)-3,8,13,18-tetramethyl-5,10,15,20,21,22, 23,24-octahydroporphyrin-2-yl]propanoic acid
3D model (JSmol)
  • InChI=1/C36H44N4O8/c1-17-21(5-9-33(41)42)29-14-26-19(3)23(7-11-35(45)46)31(39-26)16-28-20(4)24(8-12-36(47)48)32(40-28)15-27-18(2)22(6-10-34(43)44)30(38-27)13-25(17)37-29/h37-40H,5-16H2,1-4H3,(H,41,42)(H,43,44)(H,45,46)(H,47,48)
  • O=C(O)CCc1c(c5[nH]c1Cc2[nH]c(c(c2C)CCC(=O)O)Cc3c(c(c([nH]3)Cc4c(c(c([nH]4)C5)CCC(=O)O)C)CCC(=O)O)C)C
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 I is an isomer of coproporphyrinogen III, a metabolic intermediate in the normal biosynthesis of heme. The compound is not normally produced by the human body; its production and accumulation causes a type of porphyria. [1]

The difference between coproporphyrinogen I and III is the arrangements of the four carboxyethyl ("P" groups) and the four methyl groups ("M" groups). The I isomer has the sequence MP-MP-MP-MP, whereas in the III isomer it is MP-MP-MP-PM, with the last two side chains reversed.


Coproporphyrinogen I is not produced in the normal porphyrin biosynthesis pathway. However, if the enzyme uroporphyrinogen-III cosynthaseis missing or inactive, the compound uroporphyrinogen I is produced instead of uroporphyrinogen III. The enzyme uroporphyrinogen III decarboxylase will also act on the I isomer, producing coproporphyrinogen I:[2][1]

Coproporphyrinogen I synthesis from uroporphyrinogen I.png

The reaction entails the conversion of the four carboxymethyl (acetic acid) side chains to methyl groups, with release of four molecules of carbon dioxide.

Unlike the III isomer, coproporphyrinogen I (which is cytotoxic) is not further processed by the body, and accumulates. This situation occurs in the pathological condition called congenital erythropoietic porphyria.[1]


  1. ^ a b c S. Sassa and A. Kappas (2000): "Molecular aspects of the inherited porphyrias". Journal of Internal Medicine, volume 247, issue 2, pages 169-178. doi:10.1046/j.1365-2796.2000.00618.x
  2. ^ 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.