Haemoglobin, a Sulphhydryl-protein in the Binding Reaction with Radioprotective MEG

Summary

Haemoglobin (Hb) in the form of oxyhaemoglobin as a SH protein binds SH radioprotector MEG through its reactive SH-groups. Prolonged reaction time, alkaline pH and urea are able to enhance the reactivity of the unreactive (‘masked’) SH-groups of Hb to the radioprotector. The binding of MEG to the β-93 SH-groups of Hb increases the chromatographic and electrophoretic heterogeneity of the macromolecule.

On ⁶⁰Co γ-irradiation, the mixed disulphide bond between Hb and MEG is not broken but stabilized, thus provoking structural changes, resulting in denaturation. The denatured protein retains the firmly bound radioprotector; the mixed disulphide bond resists splitting with thiols after being irradiated.