Conditions were as follows: same as for Table 1, except for presence of oxidant generating systems (see Methods). Results are shown as the absolute increase in Hb oxidation rate (mean ± SD) exhibited by the complete system over that measured for the controls that deleted the enzymes. For this set of experiments, basal rates of oxidation were .029 ± .002 for HbA and .041 ± .004 for HbS. All oxidation rate increments were significant, but there were no significant differences for HbA v HbS.