A Mathematical Treatment of the Blood Dissociation Curve for Oxygen.

A quantitative description of Bohr’s effect can be made from the oxygen dissociation curves of hemoglobin at different pHs, and the dissociation constants of the 02linked acidic group of Hb (KR) and Hb02 (Ku) have been calculated as, respectively, 1.29 1O and 3.42 10-i at37#{176}. On the assumption that the oxygenation of hemoglobin takes place in four successive steps, the constant for each equilibrium can easily be calculated, and the values given. It appears that the oxygenation takes place with the same affinity for the first three steps, while the affinity for the fourth oxygenation is 125 times greater. On the basis of these results a simplification of Adair’s formula is given, containing only two constants, one (K) being representative of the affinity of the oxygen for the first three hemes, and the other (in) being the increase of affinity for the fourth oxygenation. This formula seems to fit most data in the literature of hemoglobin solutions and of blood in vivo and in vitro. The physiological effects and the functional importance of the increased affinity for the fourth oxygenation are described, and the possibility that disturbances of the Hb oxygenation process may be due to the lack of this process is considered.