Convenient synthesis of a glycopeptide analogue having a complex type disialyl-undecasaccharide

Described herein is a convenient synthesis of a glycopeptide analogue having an undecasaccharide and its stability towards peptide:N-glycosidase F (PNGase-F). To obtain the glycopeptide analogue, bromoacetamidyl undecasaccharide and undecapeptide containing a cysteine residue were synthesized and then a coupling reaction between haloacetamide and thiol was performed. The coupling reaction progressed smoothly at pH 7.0 in phosphate buffer and afforded the desired glycopeptide analogue. In addition, stability of the glycopeptide analogue thus obtained towards PNGase-F was investigated. The result indicated that the glycopeptide analogue was resistant to the enzymatic digestion.