Structural analysis of N-glycans from gull egg white glycoproteins and egg yolk IgG.
We previously showed that the expression of (Gal alpha 1-4Gal)-bearing glycoproteins among birds is related to their phylogeny. However, precise structures of (Gal alpha 1-4Gal)-containing N-glycans were only known for pigeon egg white glycoproteins and IgG. To compare structural features of (Gal alpha 1-4Gal)-containing N-glycans from other species, we analyzed N-glycans of gull egg white (GEW)-glycoproteins, ovomucoid, and ovotransferrin, and gull egg yolk IgG by HPLC, mass spectrometry (MS), and MS/MS analyses. GEW-glycoproteins included neutral, monosialyl, and disialyl N-glycans, and some of them contained Gal alpha 1-4Gal sequences. Bi-, tri-, and tetra-antennary oligosaccharides that lacked bisecting GlcNAc were the major core structures, and incomplete alpha-galactosylation and sialylation as well as the presence of diLacNAc on the branches generated microheterogeneity of the N-glycan structures. Moreover, unlike pigeon egg white glycoproteins, the major sialylation in GEW-glycoproteins is alpha2,3-, but not alpha2,6-linked sialic acids (NeuAc). In addition to the complex-type oligosaccharide, hybrid-type oligosaccharides that lack bisecting GlcNAc were also abundant in GEW-glycoproteins. Gull egg yolk IgG also contained Gal alpha 1-4Gal beta 1-4GlcNAc beta 1- sequences, but unlike pigeon IgG, no Gal alpha 1-4Gal beta 1-4Gal beta 1-4GlcNAc beta 1- sequence was detected. Bi- and tri-antennary complex-type oligosaccharides with bisecting GlcNAc and with core fucosylation as well as high-mannose-type oligosaccharides were the major structures in gull IgG. Our data indicated that some N-glycans from both GEW-glycoproteins and gull IgG contain the Gal alpha 1-4Gal beta 1-4GlcNAc beta 1- sequence, but the ratio of alpha-Gal-capped residues to non-alpha-Gal-capped residues in the nonreducing termini of N-glycans is much lower than that in those of pigeon glycoproteins.
Suzuki
Noriko
N
Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA. nrsuzuki@k.u-tokyo.ac.jp
Su
Tseng-Hsiung
TH
Wu
Sze-Wei
SW
Yamamoto
Kazuo
K
Khoo
Kay-Hooi
KH
Lee
Yuan C
YC
D000818:Animals; D046091:Charadriiformes; D004529:Egg White / Q000737:chemistry*; D004530:Egg Yolk / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry* / Q000302:isolation & purification; D007074:Immunoglobulin G / Q000737:chemistry*; D013058:Mass Spectrometry; D011134:Polysaccharides / Q000032:analysis* / Q000737:chemistry*; D013045:Species Specificity; D013997:Time Factors
D006023:Glycoproteins; D007074:Immunoglobulin G; D011134:Polysaccharides