Enhanced oxidation of bis(3,5-dibromosalicyl) fumarate alpha-alpha 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 alpha-alpha cross-linked Hb (HbXL99 alpha) at [Hb] in the 5 to 150 microM (heme) range. For increasing [Hb], the oxidation halftime (t1/2) increased for all Hbs, but t1/2 was always less for HbXL99 alpha than for HbA0 and sHb. Such feature was attributed to the lower affinity for O2 of HbXL99 alpha and may represent a serious problem for use of this Hb as blood substitute.