Electrophoretic and lectin-binding properties of glycopeptides released from the membrane during "in vitro" aging of human erythrocytes.

During in vitro aging of human erythrocytes sialopeptides are lost from the membrane in a process which appears to act on glycophorins. This glycopeptide material can be purified by affinity chromatography on Wheat germ agglutinin-Sepharose, as glycophorin does. The electrophoretic behaviour of the purified material suggests that the glycopeptide comes from the breakdown of the domain of glycophorin exposed on the surface of the membrane. The binding properties toward Phaseolus vulgaris E lectin indicate that the only N-linked sugar chain of glycophorin is present in the sialopeptide released from the membrane; therefore we can argue that the glycophorin breakdown during in vitro aging of red cell takes place beyond the 26th residue of the sequence, and probably quite near the lipid bilayer.