Structure of arabinogalactan from Larix laricina and its reactivity with antibodies directed against type-II-arabinogalactans

An arabinogalactan from wood of the larch tree (Larix laricina), which is a source of dietary fiber, is composed of d-galactose and l-arabinose in a 6:1 molar ratio accompanied by small amounts of d-glucuronic acid. The molecular mass has been determined to be 38 kDa. Linkage analysis in combination with partial hydrolysis and spectroscopic investigations revealed a 1,3-linked Galp backbone, branched at C6 to 1,6-linked Galp side residues terminated by Galp, Arap, Araf or GlcpA. Monoclonal antibodies directed against a type-II-arabinogalactan from Echinacea purpurea showed cross reactivity with the larch arabinogalactan and have been used to develop an ELISA for quantification of this polysaccharide.