Structure of the complex oligosaccharides of fetuin

• Published in: The Journal of biological chemistry Vol. 254; no. 3; pp. 789 - 795
• Main Authors: Baenziger, J U, Fiete, D
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10-02-1979
• Subjects: alpha-Fetoproteins; Carbohydrates - analysis; Glycopeptides - analysis; Methylation; Molecular Conformation; Molecular Weight; Oligosaccharides
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)37874-2

The complete structure of the complex oligosaccharides of fetuin has been established. The three fractions of complex oligosaccharide
which were isolated by ion exchange chromatography following pronase digestion (F-I, F-II, and F-III) had identical molar
ratios of sialic acid (Sia), galactose, mannose, and N-acetylglucosamine of 3:3:3:5. A combination of methylation analyses,
Smith periodate degradations, and endoglycosidase and exoglycosidase digestions were utilized to establish the structure which
is proposed to be: (see article of journal). Features of this structure not previously established include the presence of
2 residues of alpha2,3- and 1 residue of alpha2,6-linked sialic acid and their location relative to the mannose branch points.
Also unusual is the presence of an alpha-linked branch mannose with substituents at positions 2 and 4 which is in turn linked
to position 6 of the beta-linked, branch mannose. These features result in unexpected resistance to specific exoglycosidases.