Chemo-enzymatic synthesis of calcitonin derivatives containing N-linked oligosaccharides

Eel calcitonin derivatives containing various N-linked oligosaccharides were chemo-enzymatically synthesized by the transglycosylation reaction of Mucor hiemalis endo-beta-N-acetylglucosaminidase (Endo-M) to a glycosylated calcitonin derivative [Asn(GlcNac)3]-CT in which N-acetyl-D-glycosamine (GlcNAc) is attached to the L-asparagine (Asn) residue of the peptide.