Chemoenzymatic synthesis of Galα1-3Gal, Galα1-3Galβ1-4GlcNAc and their PEG-conjugates.

Galα1-3Gal-pNP was prepared enzymatically from Gal-pNP using α-galactosidase from coffee beans. PEG was attached after the reduction of nitro group into amino group to give Galα1-3Gal-PEG conjugate. After removing the pNP group in Galα1-3Gal-pNP, the obtained disaccharide was used for the synthesis of Galα1-3Galβ1-4GlcNAc and corresponding trisaccharide-PEG conjugate.