In-depth Profiling of N-glycans Isolated from Ostrich Egg White and Yolk Glycoproteomes by HPLC-HILIC-FLD-MS/MS

Abstract

Protein glycosylation is an essential post-translational modification and modulates critical cellular events. It is known that N-glycosylated proteins from egg white and yolk are played crucial roles in various cellular pathways. Characterization of N-glycan structures of glycoproteomes is required to understand these functions. Therefore, this study is aimed to characterize the N-glycan profiles of ostrich egg white and yolk glycoproteomes. In the study, N-glycans were released from ostrich egg white and yolk glycoproteomes by an enzymatical process and labeled with a procainamide tag. Samples were analyzed by HPLC-HILIC-FLD-MS/MS (high-performance hydrophilic interaction liquid chromatography with fluorescence and tandem mass spectrometric detection). The number of detected N-glycans obtained from ostrich egg white and yolk glycoproteomes was found to be 39 and 36, respectively. It was determined that N-glycans of ostrich egg white glycoproteome were highly galactosylated (96.64%). In addition, bisecting N-glycans were abundant in ostrich egg white glycoproteome (91.72%) compared to ostrich egg yolk glycoproteome (6.74%). The abundance of high-mannose N-glycans was dramatically higher in the ostrich egg yolk glycoproteome (55.84%) than the ostrich egg yolk glycoproteome (2.67%). The fucosylation ratio of N-glycans belonging to ostrich egg white and yolk glycoproteomes was detected to be 4.52% and 0.95%, respectively. The obtained data showed that N-glycan profiles of ostrich egg white and yolk glycoproteomes differed significantly.