Structural studies on oncofetal carbohydrate antigens (Ca 19-9, Ca 50, and Ca 125) carried by O-linked sialyloligosaccharides on human amniotic mucins.
Mucins were extracted from human amniotic fluid in the presence of 45% vol. phenol and separated from the bulk of smaller-sized glycoproteins by exclusion on Sephacryl S400. The mucin-fraction FW, which still contained a minute proportion of mannose, strongly expressed oncofetal antigens recognized by monoclonal antibodies C 50, NS 19-9, OC 125, Leu M1, 49 H 8, and 115 C 2. The structures of the respective mucin-linked saccharides responsible for Ca 50-, Ca 19-9-, and Lea-related antigenic activities were analyzed before or after reductive beta-elimination from sialylglycoproteins, and purification of the derived alditols by gel-permeation chromatography on Bio-Gel P-4 or high performance liquid chromatography. Two ubiquitous (FW2, FW3) and three novel oligosaccharide alditols (FW5) were characterized by f.a.b.- and e.i.-m.s., combined with methylation analysis and chromium trioxide oxidation. The OC 125 epitope on mucin-carried O-glycans was destroyed during reductive cleavage of the saccharides, indicating a conformational involvement of the reducing terminal residue and its mode of conjugation to the protein. Exoglycosidase treatment of the mucin-bound antigen revealed that the epitope structure of OC 125 includes terminal beta-D-galactosyl groups, and terminal sialyl groups that are almost inaccessible to Vibrio cholerae sialidase digestion.
Hanisch
F G
FG
Abteilung für Immunobiologie der 1. Medizinischen Universitätsklinik Köln, Federal Republic of Germany.
Uhlenbruck
G
G
Peter-Katalinic
J
J
Egge
H
H
D000653:Amniotic Fluid / Q000032:analysis*; D015295:Antigens, Tumor-Associated, Carbohydrate; D002236:Carbohydrate Conformation; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D009077:Mucins / Q000032:analysis*; D009844:Oligosaccharides; D011247:Pregnancy
D015295:Antigens, Tumor-Associated, Carbohydrate; D009077:Mucins; D009844:Oligosaccharides; C016735:sialooligosaccharides