Mucin biosynthesis. Properties of a bovine tracheal mucin β-6-N-acetylglucosaminyltransferase

P. W. Cheng, W. E. Wingert, M. R. Little, R. Wei

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

We have characterized a bovine tracheal mucin β-6-N-acetylglucosaminyltransferase that catalyses the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to the C-6 of the N-acetylgalactosamine residue of galactosyl-β1→3-N-acetylgalactosamine. Optimal enzyme activity was obtained between pH 7.5-8.5, at 5 mM-MnCl2, and at 0.06-0.08% (v/v) Triton X-100 (or Nonidet P-40), or 0.5-5.0% (v/v) Tween 20. Ba2+, Mg2+ and Ca2+ could partially replace Mn2+, but Co2+, Fe2+, Cd2+ and Zn2+ could not. Sodium dodecyl sulphate, cetylpyridinium chloride, sodium deoxycholate, octyl β-D-glucoside, digitonin and alkyl alcohols were less effective in enhancing enzyme activity, and dimethyl sulphoxide was ineffective. The apparent Michaelis constants were 1.25 mM for UDP-N-acetylglucosamine, 0.94-3.34 mM for freezing-point-depressing glycoprotein and 0.19 mM for periodate-treated blood-group-A porcine submaxillary mucin. Asialo ovine submaxillary mucin could not serve as the glycosyl acceptor. The structure of the 14C-labelled oligosaccharide obtained by alkaline-borohydride treatment of the product was identified as Galβ1→3(Glc-NAcβ1→6)N-acetylgalactosaminitol by β-hexosaminidase treatment, gas chromatography-mass spectrometry and 1H-n.m.r. (270 MHz) analysis. The enzyme is important in the regulation of mucin oligosaccharide biosynthesis.

Original languageEnglish (US)
Pages (from-to)405-412
Number of pages8
JournalBiochemical Journal
Volume227
Issue number2
DOIs
StatePublished - 1985

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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