Interaction of hemoglobin with membrane lipids: a source of pathological phenomena.

The binding of hemoglobin to phosphatidylserine liposomes was studied by Hb quenching of the fluorescence intensity of 12-(9-anthroyl) stearic acid embedded in the lipid membrane. The interaction is basically electrostatic. Hb A2 interacts more strongly than Hb A. The binding always includes an irreversible fraction. Interaction of Hb with normal red blood cell membranes was studied with the same technique. The main difference between the two systems is that the binding of Hb to the inner surface of the red cell membrane is based on the interaction of Hb with the membrane proteins and is reversible. The inner side of the red blood cell membrane is composed of phosphatidylserine lipids but these are normally masked by membrane proteins. In cases where Hb A2 is higher or when membrane lipids are abnormally exposed, Hb might interact irreversibly with the lipid layer and distort the membrane.