REGIOSELECTIVE TRANSGLYCOSYLATION IN THE SYNTHESIS OF OLIGOSACCHARIDES - COMPARISON OF BETA-GALACTOSIDASES AND SIALIDASES OF VARIOUS ORIGINS

N-Acetyl-lactosamine(beta-D-Galp-(1 --> 4)-D-GlcpNAc) was synthesized regioselectively with the aid of the transglycosylation activity of be ta-galactosidase isolated from Diplococcus pneumoniae using p-nitrophe nyl beta-D-galactopyranoside as the donor. Also, transglycosylation of the sialyl group in an (alpha-(2 --> 8)-linked sialic acid dimer or p -nitrophenyl glycoside of sialic acid to N-acetyl-lactosamine was perf ormed using sialidases of various origins. When sialidase from Clostri dium perfringens, Arthrobacter ureafaciens, or Vibrio cholerae was use d, alpha-(2 --> 6)-linked sialyl N-acetyl-lactosamine was obtained reg ioselectively. In contrast, when sialidase from newcastle disease viru s was used, the alpha-(2 --> 3)-linked isomer was obtained regioselect ively. The regioselectivity of the transglycosylation reaction using b eta-galactosidase and sialidase was compared with hydrolysis specifici ty toward the same linkages.