Interactions of Other Hemoglobin Variants with Sickle-Cell Hemoglobin

Deoxygenation-induced sickling of erythrocytes and gelling of hemolysates containing sickle-cell hemoglobin (Hb) are manifestations of the tendency of deoxyhemoglobin S in concentrated solutions to aggregate with the formation of gels or tactoids (liquid crystals). When a deoxygenated hemoglobin mixture contains both Hb S and Hb A (or certain non-Hb S variants) the nonsickling hemoglobin participates in the formation of the long gel-forming polymers, which have been observed in erythrocytes and in concentrated hemoglobin solutions. Although the precise organization of these polymers has not been defined, it is clear from clinical and laboratory investigations of patients whose red cells contain Hb . . .