Porphyrin biosynthesis. IV. 5- and 6-COOH porphyrinogens (type III) as normal intermediates in haem biosynthesis
1. 1. The role of 5- and 6-COOH porphyrinogens III in haem biosynthesis was studied in vitro. 2. 2. When haemolysates of normal chicken erythrocytes were incubated in the presence of 5- or 6-COOH porphyrinogens III, a marked isotopic dilution was observed served on the [2-12C]glycine incorporation i...
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| Autores principales: | , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_03044165_v158_n1_p79_SanMartinDeViale |
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| Sumario: | 1. 1. The role of 5- and 6-COOH porphyrinogens III in haem biosynthesis was studied in vitro. 2. 2. When haemolysates of normal chicken erythrocytes were incubated in the presence of 5- or 6-COOH porphyrinogens III, a marked isotopic dilution was observed served on the [2-12C]glycine incorporation into haem. This effect was similar and even greater than that produced by uroporphyrinogen III and coproporphyrinogen III. To confirm these results 14C-labelled porphyrinogens of 5- and 6-COOH were incubated with chicken erythrocyte haemolysates. Labelling of the haem took place in a way similar to that when [14C]uroporphyrinogen III was used. 3. 3. These results are consistent with the idea that 5-COOH porphyrinogen III and 6-COOH porphyrinogen III are normal intermediates in haem biosynthesis with a stepwise decarboxylation process of uroporphyrinogen III to coproporphyrinogen III according to the following scheme: Uroporphyrinogen III → 7-COOH porphyrinogen III → 6-COOH porphyrinogen III → 5-COOH porphyrinogen III → coproporphyrinogen III. © 1968. |
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