ROLE OF HEMIN IN THE REGULATION OF HEME-SYNTHESIS BY FETAL MOUSE-LIVER ERYTHROBLASTS IN CULTURE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 7  (4) , 183-188
Abstract
The regulatory role of exogenous hemin on the heme synthetic pathway was studied in fetal mouse liver erythroblasts in culture. Hemin added to culture medium of 13th day embryo liver cells inhibited, dose dependently, the incorporation of the porphyrin precursors, 59Fe, 14C-2-glycine and 14C-5-aminolevulinic acid (ALA) by 85%, 70% and 45%, respectively. This suggests a multiple effect of hemin on the porphyrin biosynthetic enzymes. Exogenous ALA competed with 14C-2-glycine as a porphyrin precursor, but the rate of heme synthesis, measured by 59Fe incorporation, remained unaltered. Protoporphyrin mimicked the hemin effect on the inhibition of glycine incorporation into heme, but reduced Fe incorporation by only 20%. Erythroblasts, with an inhibited porphyrin biosynthesis, utilized exogenous 59Fe-hemin for Hb assembly and maintained an undecreased level of Hb synthesis. Hemin apparently inhibits the porphyrin biosynthesis in fetal mouse liver erythroblasts mainly at the Fe incorporation stage.

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