The Ether Soluble Porphyrins Found in Urine in Acute Porphyria and Porphyria Cutanea Tarda

It has been shown that tetrapyrroles having from 4 to 8 carboxylic groups of both the III and I isomer series are formed by rabbit reticulocytes in vitro under hypoxic conditions. The tetrapyrroles of the III series are rapidly converted into protoporphyrin under aerobic conditions, while the tetrapyrroles of the I series are converted into coproporphyrinogen I. The implications of these findings have been discussed and it is suggested that an 8‐carboxylated openchained tetrapyrrolic intermediate of the I series is normally formed by a deaminase, the so‐called porphobilinogenase, and that this tetrapyrrole is condensed spontaneously into uroporphyrinogen I if this condensation is not hindered by a second enzyme, the so‐called isomerase. The possible effect of the latter is discussed and a scheme for the formation of ringformed tetrapyrroles of both the III and I series has been suggested. It is further suggested that the formation of ringformed tetrapyrroles of the I series is due to inhibition or blockage of the isomerase with spontaneous condensation into uroporphyrinogen I of the openchained tetrapyrrole of the I series formed by the deaminase, uroporphyrinogen I being rapidly converted by the decarboxylases present into coproporphyrinogen I. The accumulation of the latter when the atmosphere is changed into air, shows that the enzymes responsible for the conversion of coproporphyrinogen into protoporphyrin are highly specific and can utilize only coproporphyrinogen III and explains why porphyrins having less than 4 carboxylic groups have been found in nature only as isomers of the III series.

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Separation of Urinary Coproporphyrin Isormers I and III by Thin-Layer Chromatography Studies in Healthy Subjects and Patients with Myocardial Infarction

Koskelo

Toivonen

1966

Scandinavian Journal of Clinical and Laboratory Investigation

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The Ether Soluble Porphyrins Found in Urine in Acute Porphyria and Porphyria Cutanea Tarda

Cited by 4 publications

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Liver Disease

Liver Disease

The Formation of Coproporphyrin III and I by Rabbit Reticulocytes Under Hypoxic Conditions in Vitro

Separation of Urinary Coproporphyrin Isormers I and III by Thin-Layer Chromatography Studies in Healthy Subjects and Patients with Myocardial Infarction

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