Problems of reduced heme synthesis in reticulocytes with impaired globin synthesis.

Abstract

The mechanism by which heme synthesis is inhibited in reticulocytes with inhibited globin synthesis is not yet established. Evidence was found that the accumulated free heme does not inhibit the activity of δ-aminolaevulic acidsynthetase. The very early inhibition of heme synthesis may be caused by the effect of uncompleted globin chains or amino acids on the δ-aminolaevulic acidsynthetase or some other enzymes of the porphyrin biosynthetic chain. The accumulated free heme, the presence of which in reticulocytes with inhibited globin synthesis has been indirectly proved may reduce the iron entry to the reticulocytes which in turn can influence the synthesis of heme especially in the later periods of incubation. A feedback inhibitory effect of accumulated free heme at some critical site on the enzymes of the porphyrin biosynthetic chain cannot still be quite excluded.