Oxidative stress in β-thalassemia:: hemoglobin α-chains activate peroxidation of low density lipoproteins

Under oxidative stress normal hemoglobin (HbA) can trigger oxidation of low density lipoproteins (LDL) in the presence of hydrogen peroxide. Hb variants like isolated HbA chains possess higher peroxidative reactivity than the normal tetramer HbA. Because isolated Hb chains undergo fast autoxidation, a process yielding peroxidants, we studied the relative peroxidative activity of alpha- and beta -chains as well as of HbA without additional peroxidant. The descending order of relative oxidation of LDL protein ApoB (assessed by its crosslinking) and lipids (determined as formation of conjungated diens) was: alpha -chains > beta -chains > HbA. The results of our study indicate that extracellular chains may be the trigger of lipoproteins alterations observed in beta -thalassemia.