The Equilibrium between Oxygen and Hemoglobin in Concentrated Urea Solution

The dissociation of the horse hemoglobin molecule into 2 half molecules in 4 M urea solutions has been well established (16). The effect of concentrated urea on the equilibrium between oxygen and hemoglobin has, however, not been determined. The present experiments const.itute a study of this equilibrium. The reaction between oxygen and hemoglobin is best described if it is assumed that 4 molecules of oxygen react successively with a single molecule of hemoglobin (Hba) containing four heme groups. This assumption leads to the equations of Adair (l), of Ferry and Green (8), and of Pauling (14), all of t,he same general type; Pauling’s equation has but two constants. Between oxygen saOurations of 10 and 90 per cent, the reaction of oxygen with hemoglobin, under the conditions existing in blood, may be described approximately by the simpler equation of Hill (II),