A branched (1→3)-β- d-glucan from a sodium carbonate extract of Dictyophora indusiata fisch

Abstract

A water-soluble, (1→6)-branched, (1→3)-β- d-glucan (T-4-N), [α] D 20 +19° ( c 0.1, water), was isolated from a 2% sodium carbonate extract of the fruit bodies of Dictyophora indusiata Fisch. T-4-N was homogeneous as judged by gel filtration, Tiselius-type electrophoresis, and ultracentrifugal analysis. By gel filtration on Sepharose CL-2B, with 0.25 m sodium hydroxide as the eluant, the molecular weight of T-4-N was estimated to be ∼5.5 × 10 6. From the results of methylation analysis, periodate oxidation, Smith degradation (complete, and also mild), partial acetolysis, and enzymic degradation, it was concluded that T-4-N has a main chain composed of β-(1→3)-linked d-glucopyranosyl residues, and two single, β-(1→6)-linked d-glucopyranosyl groups attached as side chains to, on average, every fifth sugar residue of the main chain. In addition, the results of the enzymic hydrolysis suggested that the β-(1→6)-linked d-glucosyl side chains are mainly localized in the neighborhood of the nonreducing end of the main chain. The results of optical rotatory measurement and complex-formation with Congo Red indicated that T-4-N probably takes a triple-helical conformation.