Chemoenzymatic Synthesis of Neoglycopeptides:  Application to an α-Gal-Terminated Neoglycopeptide

A novel methodology for the enzymatic preparation from suitably derivatized oligosaccharides of N-linked neoglycopeptides using the microbial glutaminyl-peptide gamma-glutamyl transferase, transglutaminase (TGase), is described. N-Allyl glycosides of various oligosaccharides were photochemically coupled with cysteamine to yield amino-terminated thioether spacers, which were accepted by transglutaminase to transamidate the side-chain gamma-carboxamide group in the dipeptide Z-Gln-Gly.