Studies on the biosynthesis of blood pigments. 5. Intermediates of haem biosynthesis

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Abstract
The intermediate pathway of haem biosynthesis from glycine was investigated with a chicken-erythrocyte haemolysate preparation. The incorporation of ([alpha]-l4c) glycine into haem and simultaneously into various added porphyrins and porphyrin precursors was studied. Results indicated that porphobilinogen, and probably also [delta] -aminolaevulic acid, are true intermediates in the synthesis. None of the porphyrins tested, including uroporphyrin III, pseudouroporphyrin, coproporphyrin HI, haematoporphyrin IX and protoporphyrin DC, behaved as true intermediates in the haemolysate preparation. Added uroporphyrin III gave rise to some free protoporphyrin in the whole haemolysate, but to neither proto- nor copro-porphyrin in the supernatant preparation. Some coproporphyrin I was formed from added uroporphyrin I in both preparations. It is suggested that some compounds related to the porphyrins, rather than the porphyrins themselves, are the true intermediates in haem biosynthesis.