Quantitation of the beta-elimination reaction as used on glycoproteins.
The carbohydrate side chains of mucus-type glycoproteins are O-glycosidic bonds between N-acetylgalactosamine to the hydroxyl groups of serine and threonine in the protein core. The alkaline catalyzed beta-elimination reaction, in the presence of sodium borohydride, is used for determining the number of side chains. The present paper presents a study of the quantitativeness of the alkaline borohydride procedure, using four parameters: the loss of seryl and threonyl residues, the formation of alanine and 2-aminobutanoic acid; the decrease in N-acetylhexosamine and the recovery of the amino sugar alcohols. Bovine, ovine and porcine submandibular glycoproteins were studied. Evidence is presented for the existence of N-acetylglucosamine involvement in O-glycosidic linkages to serine and threonine. Results for the relative rates of beta-elimination indicate that serine-linked glycosides are released more rapidly than threonine-linked glycosides.
D000409:Alanine / Q000032:analysis; D000596:Amino Acids / Q000032:analysis; D001894:Borohydrides / Q000032:analysis; D002087:Butyrates / Q000032:analysis; D002625:Chemistry, Organic; D005688:Galactosamine / Q000032:analysis; D005944:Glucosamine / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis*; D006595:Hexosamines / Q000032:analysis; D055601:Organic Chemistry Phenomena; D012694:Serine / Q000032:analysis; D012709:Serum Albumin / Q000032:analysis; D013912:Threonine / Q000032:analysis
D000596:Amino Acids; D001894:Borohydrides; D002087:Butyrates; D006023:Glycoproteins; D006595:Hexosamines; D012709:Serum Albumin; D013912:Threonine; D012694:Serine; D005688:Galactosamine; D005944:Glucosamine; D000409:Alanine