Isolation and characterization of three different carbohydrate chains from melanoma tissue plasminogen activator.
Electrophoretic analysis of endoglycosidase-treated tissue plasminogen activator obtained from human melanoma cells showed that the heterogeneity observed for the protein in these preparations is caused by an N-glycosidically linked N-acetyllactosamine type of carbohydrate chain which is present in about 50% of the molecules. An oligomannose type and an N-acetyllactosamine type of glycan is present in all molecules. Three glycopeptides were isolated and characterized by 1H-NMR, sugar determination, methylation analysis and amino acid determination. The exact attachment site for each of the three glycans could be deduced from the amino acid compositions of the glycopeptides. Asn-117 carries the oligomannose type of glycan, the structure of which was completely determined. Asn-184 is the site where the presence or absence of a biantennary N-acetyllactosamine type of glycan causes the size heterogeneity. The third N-glycosylation site, Asn-448, was found to carry a triantennary or tetraantennary N-acetyllactosamine type of carbohydrate chain.
D000596:Amino Acids / Q000032:analysis; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006020:Glycopeptides / Q000302:isolation & purification; D006023:Glycoproteins / Q000302:isolation & purification; D006026:Glycoside Hydrolases; D006801:Humans; D008545:Melanoma / Q000378:metabolism*; D008745:Methylation; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000302:isolation & purification; D010959:Tissue Plasminogen Activator / Q000302:isolation & purification*
D000596:Amino Acids; D006020:Glycopeptides; D006023:Glycoproteins; D009844:Oligosaccharides; D006026:Glycoside Hydrolases; D010959:Tissue Plasminogen Activator