Isolation and partial characterization of blood group M- and N-specific glycopeptides and oligosaccharides from human erythrocytes

Abstract

Blood group M- and N-specific glycopeptides were released from the corresponding human red cells by trypsin, cleaved with pronase and separated by gel filtration. The separated, serologically specific glycopeptide fractions had activities approximately equal to those of isolated intact MN glycoproteins when measured with animal antisera and ca. 10% of these activities when determined with human antisera. M-specific glycopeptide fractions had more NAN and more components on TLE than those from N cells. Lys was not required for M or N activities. In spite of separation by repeated gel filtration, and even when only one component was found by PAGE, all glycopeptides except α-1 were inhomogeneous by TLE. Oligosaccharides of low but specific activities were released from the glycopeptides by reductive β-elimination. All oligosaccharide fractions revealed several components by TLE and TLC. Oligosaccharide fractions isolated from M-active glycopeptides had 3 major components considerably larger than a model oligosaccharide tentatively characterized as NAN-(2 → 3)- β-Gal-(1 → 3)-[NAN-(2 → 6)]-GalNActitol but N-derived ones had only 2. After desialation no difference was found between oligosaccharide fractions derived from M and N.