Detailed structural features of glycan chains derived from α1-acid glycoproteins of several different animals

The presence of hypersialylated, O-acetylated sialic acids but not disialy1 residues

Miyako Nakano, Kazuaki Kakehi*, Men Hwei Tsai, Yuan C. Lee

*Corresponding author for this work

Research output: Contribution to journalArticle

96 Citations (Scopus)

Abstract

We analyzed carbohydrate chains of human, bovine, sheep, and rat α1-acid glycoprotein (AGP) and found that carbohydrate chains of AGP of different animals showed quite distinct variations. Human AGP is a highly negatively charged acidic glycoprotein (pKa = 2.6; isoelectic point = 2.7) with a molecular weight of approximately 37,000 when examined by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and contains di-, tri-, and tetraantennary carbohydrate chains. Some of the tri- and tetraantennary carbohydrate chains are substituted with a fucose residue (sialyl Lewis x type structure). In sheep AGP, mono- and disialo-diantennary carbohydrate chains were abundant. Tri- and tetrasialo-triantennary carbohydrate chains were also present as minor oligosaccharides, and some of the sialic acid residues were substituted with N-glycolylneuraminic acid. In rat AGP, very complex mixtures of disialo-carbohydrate chains were observed. Complexity of the disialo-oligosaccharides was due to the presence of N, O-acetylneuraminic acids. Triantennary carbohydrate chains carrying N, O-acetylneuraminic acid were also observed as minor component oligosaccharides. We found some novel carbohydrate chains containing both N-acetylneuraminic acid and N-glycolylneuraminic acid in bovine AGP. Interestingly, triantennary carbohydrate chains were hardly detected in bovine AGP, but diantennary carbohydrate chains with tri- or tetrasialyl residues were abundant. Furthermore the major sialic acid in these carbohydrate chains was N-glycolylneuraminic acid. It should be noted that these sialic acids are attached to multiple sites of the core oligosaccharide and are not present as disialyl groups.

Original languageEnglish
Pages (from-to)431-441
Number of pages11
JournalGlycobiology
Volume14
Issue number5
DOIs
Publication statusPublished - May 2004

Keywords

  • α1-acid glycoprotein
  • HPLC
  • MALDI-TOF MS
  • N-acetylneuraminic acid
  • N-glycolyneuraminic acid

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