New molecular weight forms of arabinogalactan from Larix occidentalis

Arabinogalactan fractions with narrow molecular weight distributions were obtained from a crude extract of Larix occidentalis by gel-filtration chromatography. Molecular weight distributions of the fractions were determined by a combination of gel filtration chromatography (GFC) with intensity (Rayleigh) light scattering. Two distinct distributions were observed, with the fractions in the lower distribution as small as 3 kDa. A sensitive immunoassay confirmed that the polysaccharide fractions were arabinogalactans. Compositional analysis revealed that the sub-9 kDa arabinogalactan fractions obtained by gel filtration of the crude extract have significantly lower galactose to arabinose ratios than the previously isolated sub-9 kDa arabinogalactans obtained from arabinogalactan (37 kDa) by chemical methods [J.H. Prescott et al., Carbohydr. Res., 278 (1995) 113–128]. Arabinogalactan fractions were obtained from a crude extract of Larix Occidentalis. Two distinct molecular weight distributions were observed, with the fractions in the lower molecular weight distribution as small as 3 kDa. This is the first report of such a low molecular weight for Larch arabinogalactan. Fractions were identified as arabinogalactans with a sensitive immunoassay. The sub 9 kDa arabinogalactan fractions obtained from the crude extract have significantly lower galactose to arabinose ratios than the previously isolated sub 9 kDa arabinogalactans obtained from arabinogalactan (37 kDa) by chemical methods.