The Reactions of the Isolated α and β Chains of Human Hemoglobin with Oxygen and Carbon Monoxide

Abstract The values of the equilibrium and kinetic constants for the reactions with oxygen and carbon monoxide of the isolated α and β chains of human hemoglobin, both in the form with sulfhydryl groups blocked by p-hydroxymercuribenzoate and in the form with freely titratable sulfhydryl groups, have been determined. The data show clearly that the behavior of the isolated chains is not only unlike that of hemoglobin A, but also differs markedly from that of myoglobin. Since the isolated chains behave as simple systems without heme-heme interaction (n = 1 in the O2 equilibrium), they have been used to test the proposition that the binding of a ligand is correctly expressed as a single step reaction. In at least one case it appears that it is not