Oxygen Equilibrium of Human Hæmoglobin in Strong Salt Solutions

Abstract

IT has been reported by several authors that human hæmoglobin dissociates into sub-units in strong salt solutions (that is, in sodium chloride above 0.5 M). The decrease of molecular weight of hæmoglobin in such conditions was demonstrated by sedimentation^1,2, osmotic-pressure³ and light-scattering⁴ methods. According to present views⁵ on the oxygen equilibrium of mammalian hæmoglobins, the decrease in the molecular weight of hæmoglobin (and therefore the decrease in the number of the oxygen-combining centres per molecule) should be accompanied by alterations of the shape of the oxygen equilibrium curve. Taking the value of n in the Hill empirical equation: as a measure of the sigmoid character of the curve, this value should be lower than 2 for a splitting of hæmoglobin into halves⁵.