In vitro sulfation of sublingual salivary gland mucin: structures of 35S-labeled oligosaccharides

The enzyme which catalyzes the transfer of sulfate ester group from 3'-phosphoadenosine-5'-phosphosulfate to salivary mucus glycoprotein was located in the detergent extract of the Golgi-rich membrane fraction of rat sublingual salivary glands. Alkaline borohydride reductive cleavage of the synthesized 35S-labeled glycoprotein led to the liberation of the label into the reduced acidic oligosaccharide fraction. A 90.3% of the total label was found incorporated in two oligosaccharides. These were identified in order of abundance as sulfated penta- and heptasaccharides. The pentasaccharide was characterized as SO3H,6G1cNAc beta 1,3Ga1 beta 1, 4G1cNAc beta 1,3(NeuAc alpha 2,6)Ga1NAc-01, and the heptasaccharide as SO3H,6G1cNAc beta 1,3Ga1 beta 1,4G1cNAc beta 1,3Ga1 beta 1,4 G1cNAc beta 1,3(NeuAc alpha 2,6)Ga1NAc-01.