Oxidation of linolenic acid by hemoglobin.

(A) Standard reaction demonstrating the time-dependent increase in conjugated diene (A₂₃₂) formation when linolenic acid is incubated with hemoglobin in the presence of no haptoglobin, haptoglobin 1-1 (0.6 μM), or haptoglobin 2-2 (0.6 μM), as described in “Materials and methods.” Data shown are the mean ± SEM for 9 independent experiments. (B) Comparison of the percentage inhibition of hemoglobin-induced oxidation of linolenic acid by haptoglobin 1-1 or 2-2. Hemoglobin was used at a concentration of 0.62 μM, and haptoglobin was used at the concentrations shown. Data for the 2 types of haptoglobin are expressed as the percentage inhibition of oxidation that occurred in a reaction performed in parallel in the absence of any haptoglobin at the 60-minute time point. Data shown are the mean ± SEM of 9 independent experiments for each concentration of haptoglobin. *Difference in the mean percentage inhibition between haptoglobin 1-1 and haptoglobin 2-2 at that concentration was statistically significant (P < .05).