Structural studies on the carbohydrate units of armadillo submandibular glycoprotein

Albert M. Wu, Amalia Slomiany, Anthony Herp, Bronislaw L. Slomiany*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

16 Scopus citations

Abstract

The structure of carbohydrate units of the major glycoprotein fraction of armadillo submandibular gland was investigated. Alkaline borohydride reductive cleavage of the glycoprotein resulted in the release of O-glycosidically linked mono- and disaccharide units. The monosaccharide was identified as N-acetylgalactosaminitol, whereas disaccharide contained of N-acetylneuraminic acid and N-acetylgalactosaminitol. Treatment of the native and desialyzed glycoprotein with α-N-acetylgalactosaminidase resulted in the removal of 60% and 96% of N-acetylgalactosamine, respectively. No cleavage of this sugar was affected by the action of β-N-acetylhexosaminidase. Both, N-acetylgalactosamine and N-acetylneuraminic acid were susceptible to oxidation with periodate. Analyses of the partially methylated N-acetylgalactosamine derivatives, obtained from the permethylated native glycoprotein, showed the presence of 3,4,6-tri-O-methyl-N-methylacetamidogalactose and 3,4-di-O-methyl-N-methylacetamidogalactose in a ratio of 1 : 0.4. Only 3,4,6-tri-O-methyl-N-methylacetamidogalactose was found in the hydrolysates of permethylated desialyzed glycoprotein. These results together with our previous data on chemical composition of the glycoprotein suggest that about 30% of the oligosaccharide chains consist of NeuAcα2 → 6GalNAcα1 → O-Thr(Ser) and 70% of GalNAcα → O-Thr(Ser).

Original languageEnglish
Pages (from-to)297-304
Number of pages8
JournalBBA - Protein Structure
Volume578
Issue number2
DOIs
StatePublished - 19 06 1979
Externally publishedYes

Keywords

  • (Armadillo submandibular)
  • Carbohydrate unit
  • Exoglycosidase
  • Glycoprotein
  • Salivary mucin

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