Globin chain turnover in reticulocytes from patients with beta (0) -thalassaemia/Hb E disease

beta (0)-Thalassaemia/Hb E disease is the most frequent beta-thalassaemia in Thailand. However, patients have a varying degree of anaemia. The difference in severity is attributed to a differential accumulation of unpaired alpha-globin chains, which is the net result of biosynthesis and catabolism. Turnover of newly synthesized globin chains in reticulocytes from beta(0) -thalassaemia/Hb E patients was determined. Proteolysis was ATP-independent and degraded only 10-15% of the radiolabelled globin during a 4-h incubation period at 37 degrees C and there was no difference in globin turnover in reticulocytes from subjects with mild and severe forms of beta(0)-thalassaemia/Hb E. These results indicate that excess alpha-globin chains do not act as substrates for the reticulocyte proteolytic system and that the difference in severity of anaemia in beta(0)-thalassaemia/Hb E disease cannot be explained by a difference in selective post-translational catabolism.