Isolation and characterization of glycopeptides of human transcortin

Pronase digestion of human transcortin yielded two major glycopeptides (GID3 and G2D2, in a molar ratio of approx. 1.0 to 1.5) which were isolated by gel and anion-exchange chromatography. Chromatography behaviour, methylation analysis and analytical chromatography on a Con A-Sepharose column suggested that both of the glycopeptides were N-linked asparaginyl oligosaccharides of the N-acetyllactosamine type, G1D3 and G2D2 being triantennary and biantennary isoglycans, respectively. Microheterogeneity in regard to the position of the linkages between sialyl and galactosyl residues occurred in the triantennary and, possibly, in biantennary isoglycans.