Mass Spectrometric Analysis Of N-Glycans From Biological Samples

In recent years,with the immune molecules,a variety of bioactive substances have been found.scientists found that sugar not only provides energy and becomes a part of biological structure,but play an important role in protein post-translational modification.Glycosylation is associated with a variety of diseases,for instance,prostate cancer,ovarian cancer,etc.Alterations in glycosylation seem to not only affect cell growth and survival but also help tumor-induced immunomodulation.The study of glycosylation fro m model animal become more and more popular,which will promote the development of the study of glycosylation.Zebrafish,a model organism,is fit for studying vertebrate development.We analyzed the N-glycan structures of zebrafish embryos and their change during zebrafish embryogenesis to obtain data for studying the roles of N-glycosylation.In the paper,the studyof N-glycan structures of zebrafishis hampered by the glucose oligomer contaminants.We lay a path toward the efficient use of zebrafish embryos as a platform for studying glycosylation.To reduce glucose oligomer contaminants,we treat the glycoproteins with Sodium borohydride before PNGase F digestion,then the glycans were tagged with a fluorophore,2-AA by reductive-amination reaction.We analysis N-glyca n structures of zebrafish embryos by a combinatio n of HPLC.On the other hand,Glycosylamines are very potential precursors for derivatization.N-glycan have a primary amine moiety at the reducing terminus,allowing for selective derivatization with TMPP,the glucose oligomer contaminants cannot derivatization with TMPP,we established the glycomic profile of zebrafish embryos by MALDI-MS and ESI-MS.We demonstrated that,some of the complex N-glycan comprising the unusual Gal?1-4[Neu5Ac-(?2,3)] Gal?1-4[Fuc(?1,3)]GlcNAc.In addition,we found the new structure O-Acetylation of sialic acid in protein N-glycans,O-Acetyl N-glycan cause conformational change of glycoproteins and increase the hydrophobic of sialic acids,Neu5 Gc is highly and selectively enriched in beef and pork.We analyzed the N-glycan profile of embryos at 1,16,32,64,128 ring to analyze the overall structur N-glycans in zebrafish embryos.At the same time,we compare with N-glycans among four kinds of cancer cells.Studies reveal that cancer cells display their glycans at different levels of structures as compared to those observed on normal cells.These aberrant glycosylation changes in ovarian cancer may contribute to disease pathogenesis.