A model of the pH-dependence of the number of oxygen-linked chloride binding sites in hemoglobin.

A model is presented of the pH-dependence of the number of oxygen-linked chloride binding sites established by nuclear magnetic resonance quadrupole-relaxation studies on various mutant and chemically modified hemoglobins. The predictions of the model are in good qualitative agreement with the measured pH-dependences of the linewidth of the 35Cl- NMR signal. The obtained agreement implies that more chloride is bound to oxygenated than to deoxygenated hemoglobin.