In vivo conversion of 6-O-sulfo-L-galactopyranosyl residues into 3,6-anhydro-L-galactopyranosyl residues in Gracilaria chilensis Bird, McLachlan et Oliveira

The agar polysaccharides of the red seaweed Gracilaria chilensis Bird, McLachlan et Oliveira were labelled with the stable isotope C-13 by pulse feeding (NaHCO3)-C-13 to samples of this alga acclimatised to indoor culture. C-13 NMR spectroscopy of the labelled polysaccharides extracted from these samples has been used to demonstrate conversion in vivo of 6-O-sulfo-L-galactopyranosyl residues into 3,6-anhydro-L-galactopyranosyl residues. The 6-O-sulfo-L-galactopyranosyl residues can be linked to either 6-O-methyl-D-galactopyranosyl residues or D-galactopyranosyl residues. (C) 1996 Elsevier Science Ltd.