Mechanism of hemoglobin oxidation by ferricytochrome c and nitrite

The mode of hemoglobin oxidation by ferricytochrome c and nitrite was investigated by using isoelectric focus electrophoresis on Ampholine plate gel. It was found that two intermediate hemoglobins, (alpha 2 + beta 3 +)2 and (alpha 3 + beta 2 +)2 valency hybrids, were produced during the reactions, though the modes of these reactions were quite different from each other. The changes in oxyhemoglobin, (alpha 2 + beta 3 +)2, (alpha 3 + beta 2 +)2 and methemoglobin during the oxidation of hemoglobin by ferricytochrome c well fit first order kinetics. On the other hand, the changes in these hemoglobin derivatives during nitrite oxidation of hemoglobin did not fit first order kinetics, but instead were appropriate for the chain reaction models proposed by us. Since we found that superoxide anion may be involved in the reaction of hemoglobin with nitrite, a plausible reaction process was proposed. The differences in the reaction mechanism of hemoglobin oxidation by ferricytochrome c and by nitrite are discussed.