Degradation of erythrocyte glycophorin results in increased membrane bound hemoglobin.

Degradation of glycophorin by trypsin in intact red cells results in an increase in hemoglobin bound to the membrane. Incubation of resealed ghosts made from these cells demonstrated that the hemoglobin was bound to the intracellular membrane surface. We found that treatment of hemoglobin with KCNO inhibited the ability of hemoglobin to bind to the membrane. Addition of KCNO to intact cells followed by trypsin treatment abolished the additional membrane-bound hemoglobin, indicating that the bound hemoglobin resulted from increased Band 3 binding. Treatment of intact cells with neuraminidase also resulted in increased membrane-bound Hb, which correlated with the amount of sialic acid released. Scatchard analysis revealed that enzyme treatment increased the affinity of hemoglobin for the high affinity Band 3 binding site, while KCNO treatment abolished this binding. Taken together, these studies demonstrate that extracellular proteolytic degradation of glycophorin by proteases similar to those released by cells of the reticuloendothelial system results in an increased ability of hemoglobin to bind to Band 3.