Enhanced oxidation of bis(3,5-dibromosalicyl)fumarate a-a cross linked hemoglobin by free radicals generated by xanthine/xanthine oxidase

The xanthine/xanthine oxidase reaction produces reproducible amounts of oxygen-derived free radicals that oxidize human oxyhemoglobin (Hb). We monitored the kinetics of the oxidation of stripped Hb (sHb), purified HbA0 and α-α cross-linked Hb (HbXL99α) at [Hb] in the 5 to 150 μM (heme) range. For increasing [Hb], the oxidation halftime (t( 1/2 )) increased for all Hbs, but t( 1/2 ) was always less for HbXL99α than for HbA0 and sHb. Such feature was attributed to the lower affinity for O2 of HbXL99α and may represent a serious problem for use of this Hb as blood substitute.