The occurrence of l-galactose in snail galactans

Abstract

The occurrence of l-galactose ( l-Gal) was investigated in twelve preparations of snail galactans from nine different species. l-Gal (11–15%) was found not only in members of the family Helicidae, a highly developed group among the Pulmonata, but was detected also in a galactan of the oldest phylogenetic subclass of snails in the Prosobranchiata. To determine the position of the l-Gal residues, the galactans of Arianta arbustorum, Cepaea nemoralis, and Helix pomatia were methylated and hydrolysed, and the partially methylated Gal derivatives were isolated. Each derivative was O-demethylated and the ratio of d- and l-galactose was determined by g.l.c. of the trifluoroacetylated methyl glycosides using a chiral stationary phase. l-Gal (22–34%) was detected only in the tetra- O-methyl fractions, and hence l-Gal occupies exclusively terminal non-reducing positions.