earticle

영어

Ovotransferrin (OT), a multifunctional glycoprotein with defensive and protective activities, accounts for approximately 13% of chicken egg-white proteins and is known to be a major egg-associated allergen along with ovomucoid (OM). In contrast to the well-characterized N-glycans of OM, the N-glycan structure of OT has not been reported. This study used a high-performance liquid chromatography (HPLC) system equipped with a fluorescence detector and mass spectrometric analysis in combination with exoglycosidase digestion to investigate the N-glycan type and branching pattern of OT, and compared them with those of OM. The HPLC peak area was used to calculate the relative amount of each glycan. Seventeen N-glycans were identified, including 11 glycans (1core structure and 10 complex-type oligosaccharides) that are common to both OT and OM. Six characteristic glycans (two truncated structures, one complex-type oligosaccharide, and three hybrid-type oligosaccharides) in OT and eight characteristic glycans in OM were classified. OT contains the following branched complex-type structures : mono- (13.2%), bi- (23.9%), tri- (9.0%), tetra- (2.7%), and penta- (2.8%) antennary oligosaccharides; whereas OM contains mostly tri- (33.5%) and penta- (31.2%) antennary oligosaccharides. The N-glycan-containing bisecting N-acetylglucosamine comprised 43.4% and 79.8% of the total glycans in OT and OM, respectively. Moreover, circular dichroism analysis revealed that the secondary structure of the deglycosylated OT differs markedly from that of the intact protein. To our knowledge this is the first study to compare N-glycans between OT and OM.