title: Multiple Smith-degradations of carcinoembryonic antigen (CEA) and of asialo CEA.
abstract: Carcinoembryonic antigen (CEA) and asialo CEA were subjected to multiple Smith-degradation (i.e., for each degradation, application in sequence of periodate oxidation, borohydride reduction, and mild hydrolysis with acid; borohydride-t was substituted for unlabelled borohydride). High yields of modified glycoproteins were obtained at each stage. After three complete degradations and a further periodate-borohydride-t treatment, the carbohydrate content of CEA and of asialo CEA had decreased from 45-50% to 11-12% (i.e., 90% removal of carbohydrate). Glycerol was always one of the products obtained after each degradation, but threitol and erythritol were not detected. The second degradation caused a substantial loss of 2-acetamide-2-deoxyglucose, which is consistent with the location of some of this monosaccharide towards the terminal (non-reducing) end of the oligosaccharides. The "core" region of the oligosaccharides is composed of galactose, mannose, and 2-acetamido-2-deoxyglucose. After the fourth oxidation, 2-acetamido-2-deoxyglucose was 50-60% of the total content of residual carbohydrate. After the first degradation, there was a progressive loss in antigenic activity, but this was associated with a small amount of hydrolysis of the protein moiety of CEA.
mesh_terms: D000117:Acetylglucosamine / Q000032:analysis; D001894:Borohydrides; D002272:Carcinoembryonic Antigen; D055598:Chemical Phenomena; D002621:Chemistry; D005690:Galactose / Q000032:analysis; D008358:Mannose / Q000032:analysis; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis; D012794:Sialic Acids
chemical_list: D001894:Borohydrides; D002272:Carcinoembryonic Antigen; D010455:Peptides; D012794:Sialic Acids; D008358:Mannose; D000117:Acetylglucosamine; D005690:Galactose