Regioselective transglycosylation in the synthesis of oligosaccharides: comparison of β-galactosidases and sialidases of various origins

Abstract

N-Acetyl-lactosamine(β- d-Gal p-(1 → 4)- d-Glc pNAc) was synthesized regioselectively with the aid of the transglycosylation activity of β-galactosidase isolated from Diplococcus pneumoniae using p-nitrophenyl β- d-galactopyranoside as the donor. Also, transglycosylation of the sialyl group in an α-(2 → 8)-linked sialic acid dimer or p-nitrophenyl glycoside of sialic acid to N-acetyl-lactosamine was performed using sialidases of various origins. When sialidase from Clostridium perfringens, Arthrobacter ureafaciens, or Vibrio cholerae was used, α-(2 → 6)-linked sialyl N-acetyl-lactosamine was obtained regioselectively. In contrast, when sialidase from newcastle disease virus was used, the α-(2 → 3)-linked isomer was obtained regioselectively. The regioselectivity of the transglycosylation reaction using β-galactosidase and sialidase was compared with hydrolysis specificity toward the same linkages.