Subunit exchange and ligand binding: a new hypothesis for the mechanism of oxygenation of hemoglobin.

Abstract
Oxygenation of hemoglobin Involves a reaction in which oxygenated a{l dlmers exchange with deoxygenated ([alpha][beta])2 tetramers to form mixed molecules with a high O2 affinity. Oxy dimers act as allosteric effectors which bring about flie transformation of the molecule from an unreactive to a reactive conformation.