A highly efficient chemoenzymatic approach toward glycoprotein synthesis

A highly efficient endoglycosidase-catalyzed synthesis of homogeneous glycoproteins is described. By using ribonuclease B as a model system, it was demonstrated that Endo-A could efficiently attach a preassembled oligosaccharide to a GlcNAc-containing protein in a regioand stereospecific manner, when the corresponding sugar oxazoline was used as the donor substrate. The method allows the synthesis of both natural and tailor-made N-linked glycoproteins in excellent yield.