
A combined glycomics and glycoproteomics strategy was developed for the site-specific analysis of N-linked glycosylation heterogeneity from a complex mammalian protein mixture. Initially, global characterization of the N-glycome was performed using porous graphitized carbon liquid chromatography-tandem mass spectrometry (PGC-LC-MS/MS) and the data used to create an N-glycan modification database. In the next step, tryptic glycopeptides were enriched using zwitterionic hydrophilic interaction liquid chromatography (Zic-HILIC) and fractionated by reversed-phase liquid chromatography (RPLC; pH 7.9). The resulting fractions were each separated into two equal aliquots. The first set of aliquots were treated with peptide-N-glycosidase F (PNGase F) to remove N-glycans and the former N-glycopeptides analyzed by nano-RPLC-MS/MS (pH 2.7) and identified by Mascot database search. This enabled the creation of a glycopeptide-centric concatenated database for each fraction. The second set of aliquots was analyzed directly by nanoRPLC-MS/MS (pH 2.7), employing fragmentation by CID and HCD. The assignment of glycan compositions to peptide sequences was achieved by searching the N-glycopeptide HCD MS/MS spectra against the glycopeptide-centric concatenated databases employing the N-glycan modification database. CID spectra were used to assign glycan structures identified in the glycomic analysis to peptide sequences. This multidimensional approach allowed confident identification of 863 unique intact N-linked glycopeptides from 161 rat brain glycoproteins.
Brain Chemistry, Male, Glycosylation, Databases, Factual, Proteome, Biochemistry and cell biology not elsewhere classified, Molecular Sequence Data, Brain, Molecular Sequence Annotation, Hydrogen-Ion Concentration, Peptide Mapping, Rats, Biological sciences, Genetic Heterogeneity, Chemical sciences, Carbohydrate Sequence, Animals, Humans, Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase, Amino Acid Sequence, Glycomics, Protein Processing, Post-Translational, Chromatography, Liquid
Brain Chemistry, Male, Glycosylation, Databases, Factual, Proteome, Biochemistry and cell biology not elsewhere classified, Molecular Sequence Data, Brain, Molecular Sequence Annotation, Hydrogen-Ion Concentration, Peptide Mapping, Rats, Biological sciences, Genetic Heterogeneity, Chemical sciences, Carbohydrate Sequence, Animals, Humans, Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase, Amino Acid Sequence, Glycomics, Protein Processing, Post-Translational, Chromatography, Liquid
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