The effect of lead on hemoglobin-catalyzed lipid peroxidation.

Lead significantly increases the rate of hemoglobin-catalyzed lipid peroxidation. The inhibition of this effect by superoxide dismutase and catalase suggests that superoxide radicals and H2O2 are somehow involved. Furthermore, lead catalyzes methemoglobin formation both in pure hemoglobin solutions and in hemolysates in which all protecting systems are present. It is speculated that a superoxide radical released in lead-catalyzed hemoglobin autoxidation may initiate the peroxidation of unsaturated fatty acids in red cell membrane. This hypothesis is supported by the fact that the preliminary conversion of oxyhemoglobin to methemoglobin decreases the rate of peroxidation. A conclusion is drawn that in native erythrocyte Pb2+ may exert a pro-oxidant effect, possibly by interacting with hemoglobin.