Chemoenzymatic synthesis of neoglycoproteins using transglycosylation withendo-beta-N-acetylglucosaminidase A

A novel chemoenzymatic approach to synthesize neoglycoproteins containing h igh-mannose-type oligosaccharides is described. p-Isothiocyanatophenyl-beta -D-glucopyranoside (Glc-ITC) was transferred to the reducing end of the hi gh-mannose-type oligosaccharides using a transglycosylation activity of end o-beta -N-acetylglucosaminidase A (Endo-A), A novel oligosaccharide, Man(6) GlcNAc-Glc-ITC, was synthesized as a coupling reagent for lysyl and N-termi nal residues of the protein moiety. The neoglycoconjugate was coupled with several nonglycosylated proteins such as ribonuclease A, lysozyme, and alph a -lactalbumin. Between one and four high-mannose-type oligosaccharides wer e incorporated per molecule of these proteins. This method should be very u seful for the synthesis of neoglycoproteins with homogeneous high-mannose-t ype oligosaccharides. (C) 2001 Academic Press.