Specific antibodies for desialized M and N blood group antigens

Isolation and characterization of blood group N antigen precursor glycoproteins with Thomsen-Friedenreich (T) activity, N antigen precursor glycoproteins and T-active glycoproteins from cyst fluids of malignant ovarian clear cell carcinoma

1. Two perchloric acid-soluble glycoprotein fractions from cyst fluids of 2 patients with ovarian clear cell carcinoma in malignant were subjected to a systematic affinity chromatography using Vicia unijuga lectin-Cellulofine column and Arachis hypogaea lectin-Cellulofine column and separated into four glycoproteins, blood group N antigen precursor glycoprotein with Thomsen-Friedenreich (T) activity, N antigen precursor glycoprotein, T-active glycoprotein and serologically inactive glycoprotein, respectively. 2. These serologically active glycoproteins isolated in yields of 0.3-3.3% of PASFs, were proved to be mucin-type glycoproteins with Mw of 509,000-2,772,000 Da and contained 33.9-81.7% carbohydrates.

Electrophoretic and immunoelectrophoretic study of the enzymatic degradation of human orosomucoid (alpha 1 -acid glycoprotein)

Purified, intact orosomucoid (alpha 1-acid glycoprotein) derived from whole human plasma was incubated with a number of proteolytic and saccharolytic enzymes under a variety of conditions. The unfractionated digests were immediately examined by both agar gel- and immunoelectrophoresis for the presence of antigenically active (precipitating) and/or inactive macrofragments. Despite otherwise clear evidence of rapid degradation by several proteases, no antigenic subunits were detected. Among the glycosidases, almond emulsin produced a suggestion of modification of the carbohydrate moiety of a sialic acid-poor orosomucoid preparation obtained from Cohn Fr. VI, but had no effect on antigenic properties. These results are presented as further evidence for a lack of involvement of the extensive carbohydrate component of orosomucoid in its antigenic reactions, and support previous data implicating the polypeptide chain as solely responsible for its antigenicity.

Comparison of alkal-labile oligosaccharide chains of M and N blood-group glycopeptides from human erythrocyte membrane

Alkali-borohydride degradation of M or N blood-group active, tryptic glycopeptides and glycoproteins was performed under conditions giving the reduced oligosaccharides in a yield significantly improved over that reported earlier. Degradation of desialosylated glycoproteins yielded beta-D-Galp-(1 leads to 3)-D-GalNAcol, D-GalNA-col, and Galol in a ratio of approximately 30:1:1. GalNAc was shown to be alpha-D-linked to the polypeptide chain. Degradation of the glycopeptides gave the tetrasaccharide, NeuAc-(2 leads to 3)-beta-D-Galp-(leads to 3)-[NeuAc-(2 leads to 6)]-D-GalNAcol, and two trisaccharides, NeuAc-(2 leads to 3)-beta-D-Galp-(1 leads to 3)-D-GalNAcol and beta-D-Galp-(1 leads to 3)-[NeuAc-(2 leads to 6)]-D-GalNAcol, in a molar ratio of approximately 8:3:1. These oligosaccharides were accompanied by minor amounts of unidentified compounds showing identical electrophoretic mobility when derived from M and N glycopeptides. During isolation of the reduced oligosaccharides, the release of sialic acid did not exceed 5.5%, indicating that only a part of the trisaccharide portion might have arisen as a result of desialosylation of the tetrasaccharide. No differences between the degradation products derived from M and N glycoproteins were found, and the presence of significant amounts of larger, alkali-labile oligosaccharides was not observed.

Immunochemical characterization of cyanogen bromide degradation products of M and N blood-group glycopeptides

The major glycopeptides purified from the tryptic digests of M and N blood-group glycoproteins were degraded with cyanogen bromide into two fragments. The chemical composition and serological activities of the fragments obtained were determined. The results show that M and N blood-group determinants are located on the smaller N-terminal fragments, containing 8 amino acid residues and only alkali-labile oligosaccharide chains. Two of 8 amino acid residues are different in M-specific and N-specific glycopeptide. All glycopeptides obtained inhibited Vicia graminea anti-N lectin, but the N-terminal fragment of N-glycopeptide was a better inhibitor than others. Treatment with neuraminidase or acetylation of amino groups destroyed the M and N blood-group activity and increased the activity towards Vicia graminea anti-N lectin of all glycopeptides studied.