[Preparation and characterization of glycopeptides from human monoclonal immunoglobulin]

The carbohydrate composition of an human IgM myeloma protein (IgM Du) has been determined. Seventeen homogeneous glycopeptides are described and exhibit a very large microheterogeneity. They appear as two different groups : the first one contains only mannose and N-acetyl glucosamine, while the other contains N-acetyl-glucosamine, mannose, galactose, fucose, and sialic acid in variable amounts. One glycopeptide termed IX1, which contains 6 mannose and 1 N-acetylglucosamine residues is located on the terminal portion of the Fc fragment and its aminoacid sequence has been determined : Tyr-Asx-Val-Ser.