Haemoglobin Synthesis in β‐Thalassaemia

Summary. The incorporation of radioactive amino acids into the polypeptide chains of haemoglobin has been studied in reticulocyte preparations from five patients with β‐thalassaemia and four control patients. In both groups of patients an intracellular pool of free α‐chains has been found, but the pool is much larger in patients with β‐thalassaeniia major. The α‐chains exist in two forms: α‐dimers and α‐monomers, but the results suggest that they are released as dimers from the ribosomes and that the α‐chains for Hb‐A and Hb‐F synthesis are derived from the α‐dimer pool. The α‐dimers are also gradually converted to the monomers, and this may be the first stage in the denaturation of this protein. The results also show that the α‐dimer can exchange with the α‐chains of Hb‐A and that this exchange is more rapid in the presence of in vivo aged Hb‐A. In one patient with thalassaemia it was shown that there was no pool of unreleased β‐chains on the ribosomes. There is also no evidence for the release of incompleted β‐chains in our patients.