Investigation of the antigenicity of the carbohydrate moiety of chicken ovalbumin

Study on the carbohydrate specificity of antibodies formed in rabbits to synthetic glycoproteins with the carbohydrate structure of asialo-glycophorin A

Antibodies formed in rabbits to synthetic glycoproteins with the disaccharide structure beta-D-Gal-(1-3)-D-GalNAc, the carbohydrate moiety of desialylated glycophorin A, were investigated for their carbohydrate specificity by hemagglutination techniques and radioimmunoassay. The synthetic disaccharide was coupled to human serum albumin as carrier protein using different spacer groups and different configurations of the disaccharide spacer linkage. Radioimmunological inhibition experiments using a number of different derivatives of the carbohydrate group as inhibitors revealed a significant specificity of the antibodies for the oligosaccharide structure. However, the nature of the conjugation of the disaccharide to the carrier protein was found to be important for defining the specificity of the antibodies. Furthermore the arrangement of the hapten groups in the synthetic antigen had an important influence on the antigen-antibody reaction. No cross-reactions were observed between asialo-glycophorin A and the different synthetic antigens. Synthetic antigens provide a valuable tool for generating carbohydrate-specific antibodies. However, if the synthetic hapten molecule is small compared to the combining site of antibodies, the specificity of the immunological reaction is significantly influenced by the synthetic spacer arm or even the carrier protein.

Immunochemistry of O-glycosidically-linked Gal(beta 1 leads to 3) GalNAc on fragments of human glycophorin A

N-terminal and internal fragments of human glycophorin A with chemically defined carbohydrate moieties have been used as immunogens after conjugation to BSA or polymerization to produce carbohydrate-directed antibodies with the desired specificity against O-glycosidically linked D-galactopyranosyl-beta-(1 leads to 3)-N-acetyl-D-galactopyranosamine, a possible marker on transformed T-lymphocytes and mammary tissue of humans. Antisera from rabbits have been characterized by inhibition studies using 125I-labelled peptides in radioimmunoassay and by haemagglutination inhibition. The inhibition caused by natural and synthetic glycoconjugates, which have no structural correspondence with the antigen except its carbohydrates, clearly indicated the formation of antibodies specific for Gal-beta(1 leads to 3)-GalNAc in serum A3.

Isolation of two endo-beta-N-acetylglucosaminidases from fig latex

Two endo-beta-N-acetylglucosaminidases (mannosyl-glycoprotein 1,4-N-acetamidodeoxy-beta-D-glycohydrolase, EC 3.2.1.96) (type F-I and type F-II) have been isolated from fig latex. At pH 7.0, type F-1 was retained by the DEAE-Sephadex A-50 column, whereas type F-II was not adsorbed by the column. The optimum pH of type F-I was found to be pH 5.9 and type F-II, pH 5.4. Type F-I enzyme hydrolyzes the tri-mannosyl derivatives di-N-acetylglucosaminylasparagine faster than the penta- or hexa-mannosyl compounds. Type F-II hydrolyzes the penta- and hexa-mannosyl derivatives, but not the tri-mannosyl compound.