A Mechanism for the Conversion of Oxyhemoglobin to Methemoglobin by Nitrite.

摘要

Each mole of oxyhemoglobin iron converted to methemoglobin causes the oxidation of 1.5 mol of nitrite to nitrate and consumes 1 mol of protons. No oxygen is liberated. The overall reaction has two simultaneously occurring parts. In the beginning the rate-limiting reaction converting O2Hb to metHb is directly proportional to H(+) and NO2(-) concentrations and is independent of metHb. The second portion accounts in major part for the stoichiometry and rate of the overall reaction. The reaction rates at constant pH in excess nitrite are proportional to the product of the O2Hb concentration and the square of the metHb concentration.