Studies of the Oxidation-States of Hemoglobin M Boston and Hemoglobin M Saskatoon in Blood by EPR Spectroscopy

The extent of the oxidation of Hemoglobin (Hb) M Saskatoon (β63His → Tyr) and Hb M Boston (α58His → Tyr) in the patient′s blood was determined by measurement of the intensity of EPR signals at g ⊥=6.0 for the normal subunits, g 1=6.7 for the mutant subunits of Hb M Saskatoon and g 1=6.3 for those of Hb M Boston, respectively. The amounts of reduced mutant subunits were estimated from the EPR signal intensities and the amounts of Hb present as mutant Hb in the blood. About 50% and 76% of mutant subunits in Hb M Boston and Hb M Saskatoon remained reduced in the fresh blood. Gentle shaking of the blood at 37°C for 15 hours in air brought about autoxidation of the normal subunits as well as the mutant subunits of the two Hbs M, indicating that the presence of the mutant subunits facilitated autoxidation of the normal subunits. Possible involvement of NADH-metHb reductase in erythrocytes in maintenance of the reduced mutant subunits of Hb M Saskatoon was discussed.