The specificity of an alpha-(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 beta-linked D-Gal in terminal non-reducing position, forming an alpha-(1-->2) linkage. The subterminal residue and the type of interglycosidie linkage proved to be of minor importance. However, the branched trisaccharide beta-D-Gal-(1-->3)-[beta-D-Gal-(1-->6)]-beta-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.