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Branching and elongation with lactosaminoglycan chains of N‐linked oligosaccharides result in a shift toward termination with α 2→3‐linked rather than with α 2→6‐linked sialic acid residues
Author(s) -
Nemansky Martin,
Schiphorst Wietske E.C.M.,
Van den Eijnden Dirk H.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00336-8
Subject(s) - sialic acid , sialyltransferase , oligosaccharide , chemistry , biochemistry , glycan , glycoprotein , residue (chemistry) , stereochemistry , carbohydrate conformation , enzyme , alpha (finance) , branching (polymer chemistry) , polysaccharide , organic chemistry , medicine , construct validity , nursing , patient satisfaction
The activity of bovine colostrum CMP‐NeuAc: Gal β 1→4GlcNAc β ‐R α 2→6‐sialyltransferase (α6‐NeuAcT) toward oligosaccharides that form part of complex‐type, N‐linked glycans appears significantly reduced when a bisecting GlcNAc residue or additional branches are present, or when core GlcNAc residues are absent. By contrast human placenta CMP‐NeuAc:Gal β 1→4GlcNAc β ‐R α 2→3‐sialyltransferase (α3‐NeuAcT) is much less sensitive to structural variations in these acceptors. Furthermore the α3‐NeuAcT shows a much higher activity than the α6‐NeuAcT with oligosaccharides that form part of linear and branched lactosaminoglycan extensions. These results indicate that, in tissues that express both enzymes, branching and lactosaminoglycan formation of N‐linked glycans will cause a shift from termination with α 2→6‐linked sialic acid to termination with α 2→3‐linked sialic acid residues. These findings provide an enzymatic basis for the sialic acid linkage‐type patterns found on the oligosaccharide chains of N‐glycoproteins.