Studies on the biosynthesis of blood pigments. 2. Haem and porphyrin formation in intact chicken erythrocytes

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Abstract
Methods are described for the quantitative determination of the haem, protoporphyrin, coproporphyrin and uroporphyrin formed in chicken-food preparations. In whole blood, the rate of synthesis of porphyrins from glycine was constant for at least 24 hours at 38[degree]. Only one-third of the total porphyrin synthesized was present as haem, the remainder being recovered as protoporphyrin. In washed cells, haem and protoporphyrin were again formed from added glycine, but the activity of the tissue fell off more rapidly. The distribution of the free protoporphyrin between the cells and medium depended on the presence or absence of protein in the external medium. In washed cells almost all the protoporphyrin was retained inside the cells, whereas in whole blood, or in a washed-cell preparation with added serum albumin, about two-thirds of the protoporphyrin was found in the external medium. Anaerobic incubation resulted in the formation of only small amounts of coproporphyrin and of no protoporphyrin from glycine. 2:4-Dinitrophenol (10-3 [image]) completely inhibited protoporphyrin synthesis from glycine in whole blood. Added ferrous sulfate causes some increase in haem, which was accompanied by an approximately equivalent fall in free protoporphyrin. Neither asparagine nor sidero-philin has any significant effect on the utilization of iron for haem synthesis. Lead inhibited porphyrin formation from glycine, but did not apparently interfere specifically with the incorporation of iron into porphyrin. [delta] -Aminolaevulic acid was utilized by whole blood and washed-cell preparations for porphyrin synthesis. Porphobilinogen, on the other hand, does not appear to penetrate the red cell to any significant extent.