The specificity of an α-(1 → 2)-l-galactosyltransferase from albumen glands of the snail Helix pomatia

The specificity of an l-galactosyltransferase (l-Gal-T) from albumen glands of the snail Helix pomatia has been studied. This enzyme transfers l-Gal from GDP-l-Gal to various disaccharides with β-linked d-Gal in terminal non-reducing position, forming an α-(1 → 2) linkage. The subterminal residue and the type of interglycosidic linkage proved to be of minor importance. However, the branched trisaccharide β-d-Gal-(1 → 3)-[β-d-Gal-(1 → 6)]-β-d-Gal-(1 → O)Me is a very poor acceptor. The specificity of the l-Gal-T correlates well with the equimolar occurrence of l-Gal and the structural element → 2)-Gal-(1 → found in the storage polysaccharide of this snail. Since l-Fuc is also transferred from its GDP-activated form, the membrane preparations of the albumen glands can be used to synthesize fucosylated oligosaccharides. © 1997 Elsevier Science Ltd.