Structure of Fetal Lactosaminoglycan. The Carbohydrate Moiety of Band 3 Isolated from Human Umbilical Cord Erythrocytes

The structure of lactosaminoglycan prepared from Band 3 glycoprotein of umbilical cord blood erythrocytes was elucidated. The glycopeptides were digested by endo-beta-galactosidase and oligosaccharides, core glycopeptides, and intact glycopeptides were analyzed by permethylation, exoglycosidase digestion, and fast atom bombardment mass spectrometry. The structure of one of the major components was found to be: sequence in text This structure is unique in that 1) two linear polylactosaminyl chains are attached to the core portion, 2) the polylactosaminyl side chain is much longer on the Man alpha 1----6 side than on the Man alpha 1----3 side, 3) alpha 2----3-linked sialic acid is present at the terminal of the long polylactosaminyl side chain, whereas alpha 2----6-linked sialic acid is present in the other short side chain, and 4) fucose is linked only to the external position of the lactosaminyl side chain and fucose, alpha 1----6-linked to the innermost N-acetylglucosamine, is absent.