We propose that in sickle cell anemic individuals, the interaction of the abnormal hemoglobin with cytoplasmic surface of the red cell may be a primary causative factor in the formation of irreversible sickle cells. These abnormal cells can initiate microvascular occlusion and may play a major role in vasoocclusive crises. In support of such a hypothesis we propose to study the following aspects of hemoglobin-membrane interactions: a) Inside out erythrocyte membrane vesicles (IOVs) will be prepared from both normal and sickle blood types; IOVs will be characterized by marker enzymes and electron microscopy. Oxy and deoxy-hemoglobins and methemoglobins will be isolated (and/or prepared) from AA and SS blood types. The binding affinity (by certrifugation) and binding kinetics (by fluorescence quencing of a membrane embedded probe) of these hemoglobins will be studied using the respective IOVs. The specific protein(s) and/or lipid(s) from the IOV which binds to hemoglobin will be identified by photoaffinity labelling. b) The influence of various hemoglobins on the kinetics of transport of cations (K+, Na+ and Ca++) and anion (PO4---) will be studied using IOVs and resealed """"""""hybrid ghosts"""""""" (in which the desired hemoglobin type can be introduced into AA or SS membrane). c) The effect of the hemoglobin-membrane interaction on the deformability characteristics of the membrane will be studied using resealed hybrid ghosts. This will be accomplished by measuring the deformability index on an Ectacytometer. The information gathered by these studies should be helpful in understanding the sickling process; such an understanding is essential in designing a suitable drug or developing other therapeutic approaches to correct this congenital disorder, which constitutes our long-term objective.
