Demonstration of the existence of a specific blood-group P1 antigenic determinant in turtle-dove ovomucoid

Tracing the history of Galalpha1-4Gal on glycoproteins in modern birds

Galalpha1-4Gal is typically found in mammalian glycolipids in small quantities, and recognized by some pathogens, such as uropathogenic Escherichia coli. In contrast, glycoproteins containing Galalpha1-4Gal were rarely found in vertebrates except in a few species of birds and amphibians until recently. However, we had previously reported that pigeon (Columba livia) egg white and serum glycoproteins are rich in N-glycans with Galalpha1-4Gal at non-reducing termini. Our investigation with egg white glycoproteins from 181 avian species also revealed that the distribution of (Galalpha1-4Gal)-containing glycoproteins was not rare among avians, and is correlated with the phylogeny of birds. The differentiated expression was most likely emerged at earlier stage of diversification of modern birds, but some birds might have lost the facility for the expression relatively recently.

N-glycan structures from the major glycoproteins of pigeon egg white: predominance of terminal Galalpha(1)Gal

N-Glycans from major glycoproteins of pigeon egg white (ovotransferrin, ovomucoid, and ovalbumins) were enzymatically released and were reductively aminated with 2-aminopyridine, separated, and structurally characterized by mass spectrometry and a three-dimensional mapping technique using three different columns of high performance liquid chromatography (HPLC) (Takahashi, N., Nakagawa, H., Fujikawa, K., Kawamura, Y., and Tomiya, N. (1995) Anal. Biochem. 226, 139-146). Twenty-five major N-glycan structures, all of them hitherto unknown, were identified as pyridylamino derivatives. Of these, 13 were neutral, 10 were monosialyl, and 2 were disialyl oligosaccharides. All N-glycans contain from one to four Galalpha(1,4)Galbeta(1,4) sequences at the nonreducing terminal positions and are devoid of fucose residues. N-Acetylneuraminic acids were alpha(2,6)-linked only to beta-galactose. The HPLC profiles of the N-glycans from four different glycoproteins were qualitatively very similar to each other, but not identical in the peak distributions. Monosialyl glycans were most abundant in all four glycoproteins, followed by neutral glycans. Disialyl glycans were lowest in ovotransferrin, and highest in ovomucoid. Triantennary structures with bisecting GlcNAc were predominant in ovotransferrin, and tetra-antennary (with and without bisecting GlcNAc-containing) structures were predominant in other glycoproteins. Penta-antennary structures (with a sialic acid and without bisecting GlcNAc residue) were also found in small quantities in all four glycoproteins. In contrast to the chicken egg white counterparts, which contain mostly high mannose and hybrid types, all N-glycan structures in the major pigeon egg white glycoproteins are complex type.

Isolation and characterization of major glycoproteins of pigeon egg white: ubiquitous presence of unique N-glycans containing Galalpha1-4Gal

Ovotransferrin (POT), two ovalbumins (POA(hi) and POA(lo)), and ovomucoid (POM) were isolated from pigeon egg white (PEW). Unlike their chicken egg white counterparts, PEW glycoproteins contain terminal Galalpha1-4Gal, as evidenced by GS-I lectin (specific for terminal alpha-Gal), anti-P(1) (Galalpha1-4Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glcbeta1-1Cer) monoclonal antibody, and P fimbriae on uropathogenic Escherichia coli (specific for Galalpha1-4Gal). Galalpha1-4Gal on PEW glycoproteins were found in N-glycans releasable by treatment with glycoamidase F. The respective contents of N-glycans in each glycoprotein were 3.5%, POT; 17%, POA(hi); and 31-37%, POM. POA(hi) has four N-glycosylation sites, in contrast to chicken ovalbumin, which has only one. High performance liquid chromatography analysis showed that N-glycans on POA(hi) were highly heterogeneous. Mass spectrometric analysis revealed that the major N-glycans were monosialylated tri-, tetra-, and penta-antennary oligosaccharides containing terminal Galalpha1-4Gal with or without bisecting N-acetylglucosamine. Oligosaccharide chains terminating in Galalpha1-4Gal are rare among N-glycans from the mammals and avians that have been studied, and our finding is the first predominant presence of (Galalpha1-4Gal)-terminated N-glycans.

Comparative study of the primary structures of sero-, lacto- and ovotransferrin glycans from different species

In order to establish relationships between glycan structure and biological activity and to answer the question: Are glycans markers of evolution?, the authors undertook a comparative study of the glycan primary structures of different transferrins (sero-, lacto- and ovotransferrins) from several species. By associating permethylation--mass spectrometry and 1H NMR spectroscopy, the primary structure of the following transferrin glycans were determined: human, bovine, hen, horse, marsupial, mouse, rabbit, rat and sheep serotransferrins; human, mouse, bovine and goat lactotransferrins; hen and turkey ovotransferrins. The results obtained led to the conclusion that transferrin glycans are specific for each transferrin and, for a given transferrin, specific to the species. No relationship could be established a priori between primary structure and function of transferrin glycans.

Characterization of a murine monoclonal antibody specific for the human P1 blood group antigen

Four monoclonal antibodies (MAbs) directed against the P1 blood group antigen were produced by hybridomas obtained from mouse immunized with turtle-dove avomucoid. One of the MAb (154 IX B6) selected as a blood typing reagent agglutinated native P1 and Pk1 red cells with a high titer but was inactive against native P2, Pk2 and p erythrocytes. After papain treatment the reactivity towards P1 and Pk1 erythrocytes was enhanced whereas p erythrocytes remained unreactive. A weak cross-reactivity of the MAb with the Pk antigen was suspected since enzyme-treated Pk2 erythrocytes became significantly agglutinated. Further analysis of the antibody specificity was established by binding studies using neutral glycolipids prepared from P1 and P2 erythrocytes, affinity immunoabsorbents carrying known oligosaccharide structures and hapten inhibition with synthetic oligosaccharides. The MAb bound weakly to the Gal alpha 1-4Gal structure common to P1 and Pk antigens but had a marked preference for the P1 determinant (Gal alpha 1-4 Gal beta 1-4 GlcNAc) and the binding was abolished by prior treatment of oligosaccharide antigens by alpha(not beta)-galactosidase, which supports evidence that a terminal alpha-galactose residue is involved in the blood group P1 and Pk specificities. The MAb has a slightly broader specificity than the human anti-P1 counterpart but can be used safely for routine blood typing.

Primary structure of a novel N-glycosidic carbohydrate unit, derived from hen ovomucoid. A 500-MHz 1H-NMR study

The N-glycosidic carbohydrate chains of hen beta-ovomucoid were released from the protein by hydrazinolysis, and separated by HPLC. Primary structural analysis of 3 major fractions was conducted by applying 500-MHz 1H-NMR spectroscopy in combination with methylation analysis. One of the fractions investigated appeared to consist of an intersected penta-antennary structure extended with one Gal residue. The location of the latter in a certain branch could be established unambiguously by NMR. This structure is a novel member of the family of N-glycosidic carbohydrates of glycoproteins.