Structure of an amino acid-decorated exopolysaccharide secreted by a Vibrio alginolyticus strain

Abstract

Vibrio alginolyticus (CNCM I-4994) secretes an exopolysaccharide that can be used as an ingredient in cosmetic applications. The structure was resolved using chromatography and one- and two-dimensional NMR spectroscopy experiments. The results show that the carbohydrate backbone is made of two residues: D-galacturonic acid and N-acetyl-D-glucosamine (GlcNac), which together constitute a tetrasaccharide repetition unit: [→3)-α-D-GalA-(1→4)-α-D-GalA-(1→3)-α-D-GalA-(1→3)-β-GlcNAc(1→]. Two amino acids, alanine and serine, are linked to GalA residues via amido linkages. The position and the distribution of the amino acids were characterized by two-dimensional NMR spectroscopy. To our knowledge, this is the first description of a structure for a marine exopolysaccharide decorated with an amino acid.