Side reactions in the deoxygenation of dilute oxyhaemoglobin solutions by sodium dithionite

Abstract

The addition of an excess of sodium dithionite to dilute solutions of oxyhemoglobin or methemoglobin does not give a quantitative yield of hemoglobin. Side reactions occur in which part of hemoglobin is degraded to products with relatively low specific absorption. Similar reactions are induced by the brief oxygenation of dilute hemoglobin solutions containing an excess of sodium dithionite. Evidence was obtained that these reactions are brought about by an oxidation product of sodium dithionite, and involve the temporary formation of an unstable intermediate compound, which may be degraded or slowly reconverted into hemoglobin. The significance of these results in relation to quantitative spectrophotometric and kinetic measurements with oxyhemoglobin and hemoglobin is discussed.