A comparison of glycopeptides from the ovotransferrin and serum transferrin of the hen.

1. Glycopeptides were prepared from proteolytic digests of ovotransferrin and serum transferrin of the hen. The carbohydrate compositions and amino acid sequences of the peptides were studied. 2. The bulk of the carbohydrate of ovotransferrin is present as a single oligosaccharide composed of 4 residues of mannose and 8 residues of N-acetylglucosamine. Transferrin has most of its carbohydrate in a single unit composed of 2 residues of mannose, 2 residues of galactose, 3 residues of N-acetylglucosamine and either 1 or 2 residues of sialic acid. 3. The amino acid sequences of the glycopeptides carrying these different oligosaccharides are the same in ovotransferrin and serum transferrin, showing that the carbohydrate groups are attached to the same site on the protein molecule.