Glycopeptides (glycosylated peptides)
Glycopeptides (glycosylated peptides) can be divided into two principal classes:
- N-linked glycosylated peptides are the most frequently found glycopeptides
- They contain an amide bond between a glycan and the side chain of Asp, the so-called N-glycosidic bond
- The sites of N-glycosylation in N-glycoproteins are characterized by sequons Asn-Xaa-Ser/Thr (NXS/T, where Xaa is any amino acid except proline).
- The carbohydrate moiety is more variable, including alpha- and beta-Glc and beta-N-acetylgalactosamine (GalNAc)
- O-linked glycoproteins are far more diversified than N-glycoproteins
- Most abundant is the mucin-type with an alpha-linkage between GalNAc and serine or threonine
- Examples of other saccharides linked to serine and threonine include alpha-galactose (Gal), glucose (Glc), fucose (Fuc), mannose (Man) and Xylose (Xyl)
- A separate class of O-linked glycosylation, which appears to be functionally distinct, is the O-GlcNAc modification found as monosaccharides attached to either Ser or Thr
Glycosylation is the most common post-translational modification of proteins in eukaryotic cells. The carbohydrate portions of glycoproteins show a large diversity and play important roles in the distribution of these macromolecules within cells. In particular, they are recognition signals involved in intracellular communication, e.g. in cell adhesion, regulation of cell growth, infectious processes, and immunological differentiation.
A selection of glycosylated amino acids that have been successfully incorporated into glycopeptides at JPT is shown below. Please contact us for your specific request.
Please also have a look at our PTM Reference & Kits for direct usage as reference material in mass-spectrometry based proteomics to support PTM proteomics.