Glycosylation of Proteins — A Major Challenge in Mass Spectrometry and Proteomics

摘要: Although we have known for many years that most cell surface and extracellular proteins are glycosylated, only recently come to appreciate within the nucleus cytoplasm also dynamically modified by addition removal of saccharides [1]. Indeed, in eukaryotes polypeptides glycosylated. Extracellular protein-bound glycans generally complex large, whereas cytosolic nuclear often simple monosaccharides [2]. Each unique type protein glycosylation presents special challenges structural analyses or identification glycoproteins mass spectrometry (MS)[3–9]. MS cell-surface complicated enormous diversity glycan side chains, their large size, astonishing site-specific variability glycans, fact component same mass. Mass spectrometric analysis O-G1cNAc-bearing cytoplasmic is confounded highly-dynamic nature modification [10], causing sub-stoichiometric levels at single sites, inherent insensitivity method glycopeptides as compared unmodified peptides, importantly, lability saccharide linkage under analytical conditions [11, 12]. Nonetheless, all types powerful tool currently available glycoscientist interested structure/functions posttranslationally they actually occur biological systems.