J. Biol. Chem., Vol. 259, Issue 20, 12899-12907, 10, 1984
Purification and structures of oligosaccharide chains in swine trachea and Cowper's gland mucin glycoproteins
SS Rana, EV Chandrasekaran, J Kennedy and J Mendicino
Mucin glycoproteins were purified from extracts of swine trachea mucosa and
Cowper's gland. The gelatinous extracts were solubilized by reduction and
carboxymethylation and then purified by chromatography on Sepharose CL-6B
and DEAE-Sepharose. The structure of some of the carbohydrate units in
these glycoproteins were determined and compared. Alkaline borohydride
treatment indicated that more than 85% of the carbohydrate chains in these
glycoproteins were linked to serine or threonine residues in the
polypeptide chain through O-glycosidic bonds with N-acetylgalactosamine.
Reduced oligosaccharides released by treatment with alkaline borohydride
were isolated by gel filtration on Bio-Gel P-6 and chromatography on
DEAE-cellulose and paper. The structures of the oligosaccharides were
established by methylation analysis, gas chromatography, and sequential
hydrolysis with specific exoglycosidases. The major oligosaccharides in
Cowper's gland mucin glycoproteins were sialylated short chains: NeuAc
alpha 2,6GalNAcol and NeuAc alpha 2,3Gal beta 1,3(NeuAc alpha 2,6)GalNAcol.
In marked contrast, branched chains containing a Gal beta 1,3(GlcNAc beta
1,6)GalNAc core unit were the major components of trachea mucin
glycoprotein. Ten of these chains had the following structures: (Formula:
see text).