Galactosaminogalactan

Galactosaminogalactan (commonly abbreviated as GAG or GG), is an exopolysaccharide composed of galactose and N-acetylgalactosamine (GalNAc). It is commonly found in the biofilm and cell wall of various fungal species. Although the sugar residues are arranged in no particular/discrete order, and thus a heteroglycan, the residues are all linked by α-1,4 glycosidic bonds. Galactosaminogalactan is typically extracted by ethanol precipitation from liquid culture or by alkaline treatment from the cell wall. Once extracted, galactosaminogalactan becomes highly insoluble.